first cut at implementing model scene rendering
add menu item to enable/disable rendering as scene
shuffle to hopefully cleanup diff
cleanup
keep tree locked until after endScene
Merge branch 'master' of https://github.com/highfidelity/hifi into modelSceneRendering
remove warning
Merge branch 'master' of https://github.com/highfidelity/hifi into modelSceneRendering

Conflicts:
	interface/src/renderer/Model.h
handle per model transforms, default scene mode off
Merge pull request #3783 from ZappoMan/modelSceneRendering

Model scene rendering