Improve selection of view control modes

[brianchirls]

Should break it down into more usable/configurable methods for looking around.

• VR mode:
  • Always full screen
  • Render two eyes
  • Disable mouse/touch control
  • Automatically pick HMD or devicemotion
  • Disable if neither HMD or devicemotion is available
• Non-VR mode (default)
  • single camera view only
  • mouse/touch control always on (set mouse pointer)
  • manually toggle full-screen if available
  • manually toggle devicemotion if available (in case HDD MacBook has it)

Whenever we're in full-screen (VR or not), need a button to exit. Normally invisible, but revealed for a few seconds by any mousemove or touch event.

[brianchirls]

Orientation lock in VR mode if available

[brianchirls]

Make better buttons with icons. https://github.com/iconic/open-iconic