Use a scheduler instead of a thread to retrieve OAuth token
Protect orientation and rotation provider against buffer fill

On Samsung Galaxy S4 it looks like the rotation sensor delivers events
faster than cgeo can handle them during some lists operations
 (in SENSOR_DELAY_NORMAL mode).

Part of work on #4491.
Throttle the rotation display in lists to 4 Hz

There is no need to update the arrow display in list more than 4 times
per second, as this is not an instrument for precise cache hunting.

Part of work on #4491.