* 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).