Store the base matrix of HeadTrackingCamera and provice access to it It will be useful for positioning other tracked devices.
Fix a warning about a shadowed member variable
Reconstruct base camera object matrix with priority on up vector In VR it's imperative that the camera object matches reality and some applications may have a non-horizontal look vector. The up vector on the other hand should always point up in the user's immediate frame of reference.
Add functions to use absolute tracking A.k.a. room scale
Move some common calculations to base classes