Magic Cube

Fix the long-standing problem that putting app to the background would not stop the 'solving' counter.

Fix the reddening the Lock icon.

Fix a rare crash.

Introduce a BlockController - a watchdog which makes sure the Touch and UI blocks do not take too long.
If it detecs a long block, it unblocks and reports the situation to Crashylytics.

Add a 'give up' dialog - if one made at least 10 moves when solving and presses a 'back' button, one needs to confirm.

Always set the back move icon when we clear moves

Give visual indication when dragging is locked.

Change the 'Cube Back' icon when there are no moves to back.

Abstract the part that controls the 'Locked' and 'Back Moves' buttons from the two activities: the main one and the tutorial one.
This code had been duplicated there.

Add flag of Botswana.