[qtdeclarative] Pull in qsgthreadedrenderloop from upstream 'dev'

Use categorized logging for all things scenegraph.

Change-Id: I865ee838b0fd6c257b7189f24130012b98206fd1
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

Conflicts:
	src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
	src/quick/scenegraph/coreapi/qsgrenderer.cpp
	src/quick/scenegraph/qsgadaptationlayer.cpp
	src/quick/scenegraph/qsgcontext.cpp
	src/quick/scenegraph/qsgrenderloop.cpp
	src/quick/scenegraph/qsgthreadedrenderloop.cpp
	src/quick/scenegraph/qsgwindowsrenderloop.cpp
	src/quick/scenegraph/util/qsgatlastexture.cpp
	src/quick/scenegraph/util/qsgtexture.cpp
Merge pull request #33 from sletta/mer-stable

[qtdeclarative] Pull in qsgthreadedrenderloop from upstream 'dev'