Allow a fixed orientation for android tablets

[dlwalter]

Using ADB shell I can fix the orientation of the android OS on the tablet since our application is as a controller - the following command does the trick - the home screen stays fixed

adb shell content insert --uri content://settings/system --bind name:s:accelerometer_rotation --bind value:i:0
adb shell content insert --uri content://settings/system --bind name:s:user_rotation --bind value:i:3

Unfortunately QGC ignores this and will still bounce between the the 90deg and 270deg landscape modes dependent on tablet orientation.

It would be a great feature to have the option to fix the orientation of QGC to prevent auto-rotation if the controller is temporarily held upside down.