Experimental Daydream release

This is an experimental fork of ALVR targeting Daydream. It is not meant for general use. It removes the existing OculusVR SDK code and UI. It should only be used by developers comfortable with using adb install and killing the app when it misbehaves.

Known issues:

• It will hang rather than cleanly exiting. You will need to adb shell kill sometimes. You can also go to Daydream Home and relaunch it.
• Synchronization and latency are worse than the GearVR version. The previous render loop was incompatible with the Google VR SDK so it was incorrectly adapted. You may see more dropped frames than normal.
• The head and arm model are incorrect. Tracking may be strage.
• The controller mapping is incorrect. The Daydream controller doesn't have a trigger button like the GearVR controller.