Complete Scenegraph Overhaul

Cleaned up the comments, now everything in .h-files
Added a camera-class, just for test cases, non final
Added a Buffer.h Class, deleted the buffer.hpp class, but everything
works fine, i tested everything!!
Now the Scenegraph can be rendered directly in the while loop
Bug fixing 1.0

fixed bug in fbo test
Merge pull request #24 from MarcelBock/MarcelMaster

Scenegraph overhaul