Fixes a minor bug, which caused SF to promote to a bishop instead

a queen, and also recognizes draws, when the stronger side has 2 bishops of the same square color. (No real pair of bishops)

See these 2 positions:
2K5/1P6/4n3/5k2/8/8/8/B7 w - - 3 93
kn5B/8/1K6/8/8/8/8/B7 b - -

bench: 8502826

See also the discussion at Talkchess: http://talkchess.com/forum/viewtopic.php?t=50855