Using Mirroring during mini-batch training, train a new NN to output …

…an S(MG, EG) value

ELO   | 4.72 +- 3.63 (95%)
SPRT  | 10.0+0.1s Threads=1 Hash=8MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 5.00]
Games | N: 14640 W: 3152 L: 2953 D: 8535
http://chess.grantnet.us/test/7644/

ELO   | 2.71 +- 2.17 (95%)
SPRT  | 60.0+0.6s Threads=1 Hash=64MB
LLR   | 2.98 (-2.94, 2.94) [0.00, 5.00]
Games | N: 29072 W: 4423 L: 4196 D: 20453
http://chess.grantnet.us/test/7645/

BENCH : 4,601,074