Removed some missing includes
Finally, after postponed to it's max, -Wall -Werror is enabled. All warnings are fixed!
Merge branch 'master' of github.com:aevum/libgdx-cpp

Conflicts:
	src/gdx-cpp/backends/linux/LinuxGraphics.cpp
	src/gdx-cpp/graphics/g3d/loaders/wavefront/ObjLoader.cpp
	src/gdx-cpp/graphics/g3d/model/still/StillModel.cpp
Fixes on identation and warnings