Substitutes glew with glbinding
Uses glow textures and fbos. Changes Canvas in order to use Qt5 functionality and remove GL/GL.h from includes in headers
Comments canvas shortly. Uncomments source of Canvas::capture.
Refactors glow to globjects
Replaces RenderBufferObjects with glo::RenderBufferObjects
Replaces shaders and programs with glo::shader and glo::program
Removes solved TODO
Fixes crash on scene reload
Use latest globjects version. Rename qtCanvas to CanvasImplementation.
Support more then one canvas
Remove TestPainter for second canvas
WIP: Merge branch 'rendering/glow_usage' into rendering/antialiasing

Conflicts:
	source/core/CMakeLists.txt
	source/core/include/core/camera/abstractcamera.h
	source/core/include/core/painter/pipelinepainter.h
	source/core/include/core/rendering/abstractpostprocessingstage.h
	source/core/include/core/rendering/abstractrenderstage.h
	source/core/include/core/screenquad.h
	source/core/source/camera/abstractcamera.cpp
	source/core/source/painter/pipelinepainter.cpp
	source/core/source/rendering/abstractpostprocessingstage.cpp
	source/core/source/rendering/abstractrenderstage.cpp
	source/core/source/rendering/renderstage.cpp
	source/core/source/screenquad.cpp