Always evaluate space for drop games

Always evaluate space for drop games

Furthermore, consider shogi pawns in space evaluation
and fix a bug for the large board version.

crazyhouse STC (failed)
LLR: -2.97 (-2.94,2.94) [-10.00,5.00]
Total: 3008 W: 1430 L: 1519 D: 59
http://35.161.250.236:6543/tests/view/5bd9a7b96e23db7639060c3e

shogi
ELO: 36.62 +-33.5 (95%) LOS: 98.5%
Total: 400 W: 212 L: 170 D: 18

euroshogi
ELO: 34.86 +-33.4 (95%) LOS: 98.1%
Total: 400 W: 210 L: 170 D: 20

minishogi
ELO: 9.38 +-16.9 (95%) LOS: 86.2%
Total: 1000 W: 322 L: 295 D: 383

chess (large-board version)
ELO: 9.56 +-27.6 (95%) LOS: 75.1%
Total: 400 W: 137 L: 126 D: 137