started implementation of vegetation model parsing
 * changed installation directory for headers to subdirectory citygml in install/include directory
 * adapted find script to find citygml in subdirectory
Merge branch 'master' into vegetation_extraction
refs #7821, #7892

* improved parser for solitary vegetation objects and implicit geometry
* got rid of those nasty void* in the CityGMLHandler. Class Prototype FTW!
Merge pull request #1 from jklimke/develop

Develop