Boost filesystem Ver 2/3 transition

This is kind of a workaround to avoid having to maintain two variants.
Explanation: between Boost 1.42 and 1.52 there was the transition to a
reworked version of the filesystem library, itroducing some breaking changes
The new version distinguishes much clearer between the native and the
generic representation of paths -- which becomes relevant when porting
to non-POXIX operating systems.

Actually the intention was to use the generic path representation in all
configuration; currently this distinction is moot, since we're caring
only for POSIX systems.

So the workaround is to use the fsys::path::string() function, which
is available in both versions, but changed meaning to yield the native
string. Later, when able to deprecate older Boost versions, we should
switch to generic_string()

Note: an alternative solution was found by Mike Fisher in 3b39f35
using the compiletime define BOOST_FILESYSTEM_VERSION=2

See also ticket #896

src/common/basic-setup.cpp

@@ -53,9 +53,8 @@ namespace lumiera {
     string
     resolve (fsys::path iniSpec)
     {
-      string file = iniSpec.leaf();
-      string searchpath = iniSpec.branch_path().string();
-      return resolveModulePath (file, searchpath);
+      string searchpath = iniSpec.parent_path().string();                     ///////////TICKET #896
+      return resolveModulePath (iniSpec.filename(), searchpath);
     }
     
   }//(End) implementation details

src/lib/searchpath.cpp

@@ -71,7 +71,7 @@ namespace lib {
   {
     static const regex PICK_ORIGIN_TOKEN ("\\$?ORIGIN/?");
     static const string expandedOriginDir  
-      = fsys::path (findExePath()).remove_leaf().directory_string();
+      = fsys::path (findExePath()).parent_path().string() + "/";          ///////////TICKET #896
     
     return boost::regex_replace(src, PICK_ORIGIN_TOKEN, expandedOriginDir);
   }
@@ -81,24 +81,24 @@ namespace lib {
   
   
   string
-  resolveModulePath (string moduleName, string searchPath)
+  resolveModulePath (fsys::path moduleName, string searchPath)
   {
     fsys::path modulePathName (moduleName);
-    SearchPathSplitter searchLocation(searchPath);
+    SearchPathSplitter searchLocation(searchPath);                        ///////////TICKET #896
     
     while (true)
       {
         if (fsys::exists (modulePathName))
           {
             INFO (config, "found module %s", modulePathName.string().c_str());
-            return modulePathName.string();
+            return modulePathName.string();                               ///////////TICKET #896
           }
         
         // try / continue search path
         if (searchLocation.isValid())
           modulePathName = fsys::path() / searchLocation.next() / moduleName;
         else
-          throw error::Config ("Module \""+moduleName+"\" not found"
+          throw error::Config ("Module \""+moduleName.string()+"\" not found"   /////TICKET #896
                               + (searchPath.empty()? ".":" in search path: "+searchPath));
   }   }
   

src/lib/searchpath.hpp

@@ -111,7 +111,7 @@ namespace lib {
    *  @return the absolute pathname of the module file found
    *  @throws error::Config when the resolution fails  
    */
-  string resolveModulePath (string moduleName, string searchPath = "");
+  string resolveModulePath (fsys::path moduleName, string searchPath = "");