Fix use of newer API
Remember to return true after handling menu commands
Drop unused member
Move some GestureHandler members to subclass
Consolidate two flags into an int
Add action to enter full-screen mode
Add four-finger tap gesture to exit fullscreen

Android < 4.4 doesn't have a global gesture for exiting fullscreen.
Reduce visibility of several RemoteCanvasActivity methods
Stop setting fullscreen _LAYOUT_ flags

We seem to miss some viewport size updates when we conditionally set
the flags.
Hide/show action bar from onSystemUiVisibilityChange callback

This should ensure the action bar state can never get out of sync with
the fullscreen state.
Have SpiceCommunicator set isInNormalProtocol itself