Wrong_bishop_fix

For most cases, this should fix the problem of not recognizing draws with wrong-coloured bishop endgame.
Following positions are now solved:
8/8/2B1b3/8/8/2k5/6PP/5K2 b - - 0 1
1k5n/8/2K5/8/P7/P7/1B6/8 w - - 2 1

I simply skip futility-pruning in qsearch, when we are in very late endgame. Not very elegant, but effective. And it should hardly have a noticeable drawback at this late stage of the game.

bench: 7604295

Of course, the decision whether you commit or not, is up to you, Marco.