* All attribute pointers and buffer binding is now stored in each
mesh own vertex array object, thus each mesh drawing now needs
only three OpenGL calls.
* Removed default VAO from Scene, which fixes unit test crashes.
Qt is needed only for building tests, thus it is in makedepends, GLEW on
the other hand is needed all the time, as it is dynamic library. Mesa is
dependency of GLEW, thus removing it.