Disable null move pruning for horde chess

Disable null move pruning for horde chess

horde STC
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 2289 W: 1212 L: 1076 D: 1
http://35.161.250.236:6543/tests/view/5c249b6d6e23db2472895633

horde LTC
LLR: 2.96 (-2.94,2.94) [0.00,10.00]
Total: 863 W: 488 L: 373 D: 2
http://35.161.250.236:6543/tests/view/5c24b2ea6e23db2472895639

giveaway STC
LLR: 2.95 (-2.94,2.94) [-10.00,5.00]
Total: 1213 W: 398 L: 356 D: 459
http://35.161.250.236:6543/tests/view/5c249ba06e23db2472895636

giveaway LTC
LLR: 2.99 (-2.94,2.94) [-10.00,5.00]
Total: 801 W: 268 L: 223 D: 310
http://35.161.250.236:6543/tests/view/5c24d7466e23db247289563c