Factory background, plus bugfixes

Added factory model for background.
Changed cursor to orange for visibility against factory walls.
Fixed a bug in the previous bugfix for the Hydra analog stick.
Fixed a bug in cursor calibration.
Inverted view controls so it feels like you're adjusting the 'camera'.
Removed zoom controls - they're redundant with
hold_to_adjust_view_button and move the wand toward/away from the
screen.
Prevented everything from going partially transparent when adjusting
view.
Tuned starting position of cursor for the one-hand Hydra configuration.