Enable BufferedDrawer support in GraphicsScene for HELIUM_TOOLS
Fix singleton destroy methods to call Shutdown
Clean up EditorEngine
Merge branch 'master' of https://github.com/HeliumProject/Helium

Conflicts:
	Editor/EditorEngine.cpp
	Editor/EditorEngine.h
	Editor/ViewCanvas.cpp
	SceneGraph/Viewport.cpp
	SceneGraph/Viewport.h
Merge branch 'master' of https://github.com/HeliumProject/Helium