Tweak piece values for losing chess variants

Tweak piece values for losing chess variants

giveaway STC
LLR: 2.96 (-2.94,2.94) [0.00,10.00]
Total: 968 W: 416 L: 320 D: 232
http://www.variantfishtest.org:6543/tests/view/5e4c62af6e23db46beba4e49

giveaway STC
LLR: 2.96 (-2.94,2.94) [0.00,10.00]
Total: 808 W: 338 L: 247 D: 223
http://www.variantfishtest.org:6543/tests/view/5e4cdfff6e23db46beba4e60

losers STC
LLR: 2.95 (-2.94,2.94) [0.00,10.00]
Total: 1862 W: 903 L: 783 D: 176
http://www.variantfishtest.org:6543/tests/view/5e4c62c36e23db46beba4e4c

losers LTC
LLR: 2.95 (-2.94,2.94) [0.00,10.00]
Total: 3538 W: 1617 L: 1476 D: 445
http://www.variantfishtest.org:6543/tests/view/5e4ce00a6e23db46beba4e62