* introduce a lumiera_preinit() which does some dirty startup work
* lumiera_init() and lumiera_shutdown() will do the desired
DesignProcess/GlobalInitilaization
* as example, initialize the config interface there
This exports the 'configuration' system as interface. It is not finally
settled if the filenames shall be *_interface.{c,h} and some details might
be sorted out (so far it works quite well).
This can also serve as example how to implement a slightly more complex
interface (some functions got inline wraped because we dont want to export
internal config system state).
Plugins which in turn want to open other interfaces need some way to
access the interfaces system itself. This is realized with a 'interface'
implementing the interface api and passed to the plugins initialization
routine.
A plugin which wishes to open other interfaces must
safe this in a local variable defined by LUMIERA_PLUGIN_INTERFACEHANDLE
with the LUMIERA_PLUGIN_STORE_INTERFACEHANDLE macro.
The LUMIERA_INTERFACE_OPEN and LUMIERA_INTERFACE_CLOSE macros change their
definition depending on compiled as buildin or plugin to account for that.
* fixed include paths
* lots of build system fixes
* initialization, shutdown, state and nobug flags are factored out into
a liblumierainit.a to simplify test builds
This starts the proposed changes in
http://www.pipapo.org/pipawiki/Lumiera/DesignProcess/ApplicationStructure
* Moving all necessary files from src/backend to src/lumiera
* create a small helloworld main app
* setup the buildsystem to build it all
* fix include paths at many places
The testsuite is not yet fixed here, that will be the next commit
