Blender Git Loki

Disable zooming/pannig of HMD view while in camera perspective

Applying zoom to projection matrix wouldn't be correct, applying it to
the view matrix would work, but not easy to do it nicely. We'd also
still miss vertical/horizontal offset since it's realized using lens
shifting (= modifiying projection matrix), so that had to be applyied
onto view matrix as well.
Decided to just disallow paning and zooming completely for now, I don't
think it would make much sense in camera perspective.