clean-up: update links embedded into API-doc (Doxygen)

Notably some links on the **Gnome documentation** pages are problematic,
since there was seemingly an infrastructure change -- which unfortunately
leads to loosing several deep-links into the GTK-3 related documentation
and tutorials.

While the differences to GTK-4 are often rather minimal, I would still prefer
to link to those documentation pages used as reference at implementation time
of our related library and GUI functionality.

In several cases I have thus looked up the old URLs at Archive.org

src/common/option.hpp

@@ -25,7 +25,7 @@
  ** various _alternative modes,_ like starting "headless" (without UI), script
  ** driven or as node in a renderfarm network.
  ** 
- ** [Boost program options library] : http://www.boost.org/doc/libs/1_55_0/doc/html/program_options.html
+ ** [Boost program options library] : https://www.boost.org/doc/libs/1_83_0/doc/html/program_options.html
  ** 
  ** @see basic-setup.hpp
  ** @see lumiera::AppState

src/lib/format-obj.cpp

@@ -184,7 +184,7 @@ apologies for that."
    *   the cache, so it doesn't make much of a difference if we scan
    *   the same comparatively short string multiple times
    * 
-   * [stdRegEx-threadsafe]: http://stackoverflow.com/questions/15752910/is-stdregex-thread-safe
+   * [stdRegEx-threadsafe]: https://stackoverflow.com/questions/15752910/is-stdregex-thread-safe
    */
   string
   humanReadableTypeID (Literal rawType)

src/lib/hash-standard.hpp

@@ -38,7 +38,7 @@
  ** push it aside and plant our own definition instead.
  ** 
  ** @note this trick was proposed by user "enobayram" on Stackoverflow at Oct 5, 2012
- ** http://stackoverflow.com/questions/12753997/check-if-type-is-hashable
+ ** https://stackoverflow.com/questions/12753997/check-if-type-is-hashable
  ** 
  ** @warning this header <b>includes and manipulates</b> the standard header `<functional>`.
  **       Please ensure it is always included _before_ the latter. Failing to do so will result

src/lib/ios-savepoint.hpp

@@ -25,7 +25,7 @@
  ** @see IosSavepoint_test
  ** 
  ** [qbert220]: https://stackoverflow.com/users/617617/qbert220
- ** [stackoverflow]: https://stackoverflow.com/a/18822888 "Restore state of `std::cout` after manipulating it"
+ ** [stackoverflow]: https://stackoverflow.com/questions/2273330/restore-the-state-of-stdcout-after-manipulating-it/18822888#18822888 "Restore state of `std::cout` after manipulating it"
  ** 
  ** 
  */

src/lib/meta/function.hpp

@@ -135,8 +135,8 @@ namespace meta{
    *          unless you bind it beforehand into a std::function with correct signature.
    * @see FunctionSignature_test
    * 
-   * [kennytm]: http://stackoverflow.com/users/224671/kennytm
-   * [stackoverflow]: http://stackoverflow.com/questions/7943525/is-it-possible-to-figure-out-the-parameter-type-and-return-type-of-a-lambda/7943765#7943765 "figure out parameter and return type of a Lambda"
+   * [kennytm]: https://stackoverflow.com/users/224671/kennytm
+   * [stackoverflow]: https://stackoverflow.com/questions/7943525/is-it-possible-to-figure-out-the-parameter-type-and-return-type-of-a-lambda/7943765#7943765 "figure out parameter and return type of a Lambda"
    */
   template<typename FUN, typename SEL =void>
   struct _Fun

src/lib/meta/typeseq-util.hpp

@@ -48,7 +48,7 @@ namespace meta {
   /**
    * Find the index of the first incidence of a type in a type-sequence.
    * @note static assertion if the type is not in the type sequence
-   * @see https://stackoverflow.com/a/60868425/444796
+   * @see https://stackoverflow.com/questions/18063451/get-index-of-a-tuple-elements-type/60868425#60868425
    */
   template<class X>
   constexpr size_t

src/lib/meta/util.hpp

@@ -81,7 +81,7 @@ namespace meta {
    *          variant here, which is slightly stripped down and a tiny bit
    *          more concise than the boost variant. This way, we can avoid
    *          a lot of boost inclusions, which always bear some weight.
-   * @see [std::enable_if](http://en.cppreference.com/w/cpp/types/enable_if)
+   * @see [std::enable_if](https://en.cppreference.com/w/cpp/types/enable_if.html)
    */
   template <class Cond, class T = void>
   using enable_if = enable_if_c<Cond::value, T>::type;

src/lib/nocopy.hpp

@@ -20,7 +20,7 @@
  ** with mutable state and confusion regarding equality.
  ** @remark inspired by [Boost-Noncopyable]
  ** 
- ** [Boost-Noncopyable]: http://www.boost.org/doc/libs/1_55_0/libs/utility/utility.htm#Class_noncopyable
+ ** [Boost-Noncopyable]: https://www.boost.org/doc/libs/1_55_0/libs/utility/utility.htm#Class_noncopyable
  */
 
 

src/lib/random.hpp

@@ -19,7 +19,7 @@
  ** For simplified usage, two default instances are exposed as global variable
  ** - lib::defaultGen uses fixed seeding (planned: make this configurable)
  ** - lib::entropyGen always uses true randomness as seed value.
- ** [C++ random number framework]: https://en.cppreference.com/w/cpp/numeric/random
+ ** [C++ random number framework]: https://en.cppreference.com/w/cpp/numeric/random.html
  ** @see Random_test
  */
 

src/lib/thread.hpp

@@ -108,7 +108,7 @@
  **    C++ standard library. Design and semantics were retained, while implemented
  **    using modern features, notably the new _Atomics_ synchronisation framework.
  **
- ** [syncs-with definition] : https://en.cppreference.com/w/cpp/atomic/memory_order#Synchronizes_with
+ ** [syncs-with definition] : https://en.cppreference.com/w/cpp/atomic/memory_order.html#Synchronizes_with
  */
 
 

src/lib/time/timevalue.hpp

@@ -735,7 +735,7 @@ namespace time {
   /** derive a hash from the µ-tick value
    * @return rotation of the raw value to produce a suitable spacing for consecutive time
    * @remark picked up by Boost-hash, or std. hashtables with the help of `hash-standard.h`
-   * @see https://stackoverflow.com/a/31488147
+   * @see https://stackoverflow.com/questions/31387778/near-constant-time-rotate-that-does-not-violate-the-standards/31488147#31488147
    */
   inline HashVal
   hash_value (TimeValue const& time)

src/lib/uninitialised-storage.hpp

@@ -52,7 +52,7 @@
  ** - an implicit conversion path to the corresponding array type is provided
  ** - subscript operators enable direct access to the raw storage
  ** - helper functions allow for placement new and delete.
- ** [deprecated again]: https://stackoverflow.com/a/71828512
+ ** [deprecated again]: https://stackoverflow.com/questions/71828288/why-is-stdaligned-storage-to-be-deprecated-in-c23-and-what-to-use-instead/71828512#71828512
  ** @see extent-family.hpp
  ** @see vault::gear::TestChainLoad::Rule where this setup matters
  */

src/lib/util-quant.hpp

@@ -171,7 +171,7 @@ namespace util {
    * @see ZoomWindow_test
    * 
    * [ToddLehman]: https://stackoverflow.com/users/267551/todd-lehman
-   * [stackoverflow]: https://stackoverflow.com/a/24748637 "How to do an integer log2()"
+   * [stackoverflow]: https://stackoverflow.com/questions/994593/how-to-do-an-integer-log2-in-c/24748637#24748637 "How to do an integer log2()"
    */
   template<typename I>
   inline constexpr int

src/lib/verb-visitor.hpp

@@ -64,8 +64,8 @@
  ** special twist that we don't use a pre-bound function, but rather need to combine the
  ** actual invocation target at the moment of the invocation.
  ** 
- ** [member pointer]: https://en.cppreference.com/w/cpp/language/pointer
- ** [std::apply]: https://en.cppreference.com/w/cpp/utility/apply
+ ** [member pointer]: https://en.cppreference.com/w/cpp/language/pointer.html
+ ** [std::apply]: https://en.cppreference.com/w/cpp/utility/apply.html
  ** 
  ** @see [drawing on the track canvas](\ref body-canvas-widget.cpp)
  ** @see VerbVisitorDispatch_test

src/stage/ctrl/state-map-grouping-storage.hpp

@@ -183,8 +183,8 @@ namespace ctrl {
        *    comparator has to define a suitable `operator()` and in addition a marker type
        *    `is_transparent`. See [transparent-cmp] and the [reference][cind-cpp14] for explanation.
        *                                                                            //////////////////////////////////TICKET #991
-       * [find-cpp14]: http://en.cppreference.com/w/cpp/container/set/find
-       * [transparent-cmp]: http://stackoverflow.com/questions/20317413/what-are-transparent-comparators
+       * [find-cpp14]: https://en.cppreference.com/w/cpp/container/set/find
+       * [transparent-cmp]: https://stackoverflow.com/questions/20317413/what-are-transparent-comparators
        */
       static GenNode const&
       getState (Record const& entry, string propertyKey)

src/stage/ctrl/ui-dispatcher.hpp

@@ -56,8 +56,8 @@
  **       given receiver thread (here the UI event loop thread) will _share a single pipe for signalling._
  **       Under heavy load this queue might fill up and block the sender on dispatch.
  ** 
- ** [Glib-Dispatcher]: https://developer.gnome.org/glibmm/2.42/classGlib_1_1Dispatcher.html
- ** [GTKmm-tutorial]:  https://developer.gnome.org/gtkmm-tutorial/3.12/sec-using-glib-dispatcher.html.en
+ ** [Glib-Dispatcher]: https://web.archive.org/web/20210306110019/https://developer.gnome.org/glibmm/2.42/classGlib_1_1Dispatcher.html
+ ** [GTKmm-tutorial]:  https://gnome.pages.gitlab.gnome.org/gtkmm-documentation/sec-using-glib-dispatcher.html
  ** @see NotificationService
  ** @see CallQueue_test
  */

src/stage/dialog/test-control.hpp

@@ -113,7 +113,7 @@ namespace dialog {
    * struct, which is actually heap allocated and managed automatically. This way, each child page
    * gets its own namespace, and wiring to other components is made explicit by passing named ctor
    * arguments -- while the overall structure  of building and wiring of widgets stays close to the
-   * habits of [programming with GTKmm](https://developer.gnome.org/gtkmm-tutorial/stable/).
+   * habits of [programming with GTKmm](https://gnome.pages.gitlab.gnome.org/gtkmm-documentation/).
    * - define the pages as custom widgets, typically just as locally known struct types
    * - invoke #buildPage passing the type and tab label for each page
    * - define the wiring of the components within a page in the page's ctor
@@ -121,7 +121,7 @@ namespace dialog {
    * @note the page widgets are actually heap allocated and managed automatically
    * @see stage::dialog::TestControl as a usage example
    * 
-   * [Notebook]: https://developer.gnome.org/gtkmm-tutorial/stable/sec-multi-item-containers.html.en#sec-notebook
+   * [Notebook]: https://gnome.pages.gitlab.gnome.org/gtkmm-documentation/sec-multi-item-containers.html#sec-notebook
    */
   class Notebook
     : public Gtk::Notebook

src/stage/model/tangible.hpp

@@ -108,8 +108,8 @@
  ** These slots are defined to be `sigc::trackable` for automated disconnection
  ** see [sigc-track] for an explanation.
  ** 
- ** [MVC-Pattern]: http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
- ** [sigc-track]: http://issues.lumiera.org/ticket/940#comment:3 "Ticket #940"
+ ** [MVC-Pattern]: https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
+ ** [sigc-track]: https://issues.lumiera.org/ticket/940#comment:3 "Ticket #940"
  ** 
  ** @see \ref AbstractTangible_test
  ** @see \ref BusTerm_test

src/stage/model/w-link.hpp

@@ -37,7 +37,7 @@
  **          a dead functor. We make use of the same mechanism here to
  **          install a callback to invalidate this smart-handle.
  ** 
- ** [trackable]: https://developer.gnome.org/libsigc++/stable/structsigc_1_1trackable.html#details "`sigc::trackable`"
+ ** [trackable]: https://libsigcplusplus.github.io/libsigcplusplus/reference/html/structsigc_1_1trackable.html#details "`sigc::trackable`"
  ** 
  ** @see \ref WLink_test
  ** @see \ref NotificationHub (usage example)

src/stage/ui-bus.hpp

@@ -83,7 +83,7 @@
  ** @see ctrl/nexus.hpp
  ** @see ctrl/core-service.hpp
  ** 
- ** [MVC-Pattern]: http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
+ ** [MVC-Pattern]: https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
  */
 
 

src/stage/widget/error-log-display.hpp

@@ -190,7 +190,7 @@ namespace widget {
        *  but also stores a [Mark] to bookmark the presence of this
        *  error entry. And finally expand the display if collapsed.
        *  
-       * [Mark]: https://developer.gnome.org/gtkmm-tutorial/stable/sec-textview-buffer.html.en#textview-marks
+       * [Mark]: https://gnome.pages.gitlab.gnome.org/gtkmm-documentation/chapter-textview.html#textview-marks
        */
       void
       addError (string text)
@@ -303,9 +303,9 @@ namespace widget {
        *         The handling of marks and tags is described in the [GTKmm tutorial].
        * @warning Each entry creates a new pair of marks. Not sure about the impact on performance...
        * 
-       * [GTKmm tutorial]: https://developer.gnome.org/gtkmm-tutorial/stable/sec-textview-buffer.html.en#textview-marks
-       * [insert-mark]: https://developer.gnome.org/gtkmm/3.22/classGtk_1_1TextMark.html#details
-       * [API doc]: https://developer.gnome.org/gtkmm/3.22/classGtk_1_1TextView.html#a8412941c4da9a71a381052d6049164e4
+       * [GTKmm tutorial]: https://gnome.pages.gitlab.gnome.org/gtkmm-documentation/chapter-textview.html#textview-marks
+       * [insert-mark]: https://web.archive.org/web/20210306120221/https://developer.gnome.org/gtkmm/3.22/classGtk_1_1TextMark.html#details
+       * [API doc]: https://web.archive.org/web/20210306120223/https://developer.gnome.org/gtkmm/3.22/classGtk_1_1TextView.html#a8412941c4da9a71a381052d6049164e4
        */
       Entry
       addEntry (string const& text, Literal markupTagName =nullptr)

src/steam/control/command-def.hpp

@@ -247,7 +247,7 @@ namespace control {
   
   /**
    * Helper class used solely for _defining_ a Command-Object.
-   * This technique is known as "fluent API", see http://en.wikipedia.org/wiki/Fluent_interface
+   * This technique is known as "fluent API", see https://en.wikipedia.org/wiki/Fluent_interface
    * The basic idea is for the user to create a disposable instance of this definition helper,
    * only for calling a chain of definition functions, which internally build the actual Command object.
    * Finally, the created Command object will be stored into a registry or handed over to the

tests/library/util-identity-test.cpp

@@ -48,7 +48,7 @@ namespace test {
    *         pointers, disregarding any type information, thereby
    *         _»unpacking«_ the address information contained in a
    *         pointer is (i.e. the address of the pointee is used)
-   * [object]: https://en.cppreference.com/w/cpp/language/type
+   * [object]: https://en.cppreference.com/w/cpp/language/type.html
    */
   class UtilIdentity_test : public Test
     {