MC playout needs to playout until everything is settled.

[kalliduz]

Currently, there is a small possibility, that two player pass after each other in MC playout. This possibility actually grows when coming to the end of the playout, since passmove is just another valid move in the playout.

But since the fast score calculation is inaccurate for partly unsettled areas, we should just play all moves that aren't seki, suicide or eye-killing before we allow pass moves in the playout.