feature request: improved undo

[labriola]

Thanks for adding the undo logic. Right now, if you tap the wrong spot, you need to wait until white has moved to undo. When playing on upper level ai, that could be a minute or two before you can take back a mis-tap. Any chance of allowing undo before white moves? It would help immensely.

[gthazmatt]

I've recently noticed that this is actually possible to undo immediately now, however, it usually causes the game to crash.