* fix: collection of vr fixes
Node: additionalTransform() has its own dirty variable
VR: disabling VR works as expected
VR: works with camera3d test
VR: iOS Tracking works even if it doesn't have any input
fix: setNodeToParentTransform() and setAdditionalTransfrom() work...
...at the same time.
Also, this PR makes the size of Node smaller. `_additionalTransform` is
no longer an inline object.
Instead, it is allocated on demand making 99% of the Nodes smaller by 60
bytes.
fix: compile in windows
* doc: documentation for this fix
James Chen