"Opponent Worsening" in RFP

[jhonnold]

Bench: 2625158

Idea from Stockfish. If the opponents last move decreases the static evaluation of the position for them, then slightly increase the possibility of RFP.

Elo   | 1.65 +- 1.24 (95%)
SPRT  | 10.0+0.10s Threads=1 Hash=8MB
LLR   | 2.91 (-2.25, 2.89) [0.00, 2.00]
Games | N: 79656 W: 19260 L: 18881 D: 41515
Penta | [257, 9340, 20285, 9659, 287]
http://chess.grantnet.us/test/38374/

Elo   | 1.11 +- 0.90 (95%)
SPRT  | 60.0+0.60s Threads=1 Hash=64MB
LLR   | 2.89 (-2.25, 2.89) [0.00, 2.50]
Games | N: 132546 W: 30745 L: 30323 D: 71478
Penta | [97, 14681, 36303, 15087, 105]
http://chess.grantnet.us/test/38375/