New version of Backgammon

[Gulchen]

I don't play backgammon, so maybe this was already implemented, but I'm bringing attention back to

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Let us assume a match to 7 and player A leads 5-1.

If during the next game player B doubles and A accepts then the doubling cube moves from the middle to player A's side. But it is a dead cube
for player A, by rule! The BG implementation must (!) grey out the cube and it is an illegal move for player A to redouble in this situation!

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Finally, less important: At the score of 5-1 for player A and an accepted cube to 2, if player A
wins a (doubled) gammon, the final score is not 9-1 but it is 7-1. The winner always gets 7 points.

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just in case.

[Moof]

Thank you for feebacks, I will check this very soon.

[Moof]

I just pushed a new version with a few fixes, added a better undo, improved the pawn selection.
About forfeit and double, I couldn't reproduce what was wrong, or maybe I didn't understand. If you can make a bug report, it would be better for me.
Thank you!

[euklid314]

I have started a request for a turn based 7-point match of backgammonmf. If someone that can play 1-2 moves per day wants to join I can test the version as well.