correct z-near, z-far for Irrlicht engine
simplify scene nodes
Revert "correct z-near, z-far for Irrlicht engine"

This reverts commit 4fce2be9dd9e3cf6480137bea5bd19b43bd497e9.
Revert "simplify scene nodes"

This reverts commit 388f7b8c6d68e024ab737627e8807c4a8e88b3ee.
redo revert
decorate scene manager to extend its abilities
clean up
implement basic Rift support
reimplement head tracking
clean up resource dir
Merge branch 'COVRSceneManagerDecorator' into test

Conflicts:
	Source/main.cpp