⚖ Protected pawn bonus

[eduherminio]

Score of Lynx-eval-protected-pawns-2947-win-x64 vs Lynx 2938 - main: 1518 - 1659 - 1925  [0.486] 5102
...      Lynx-eval-protected-pawns-2947-win-x64 playing White: 1060 - 508 - 984  [0.608] 2552
...      Lynx-eval-protected-pawns-2947-win-x64 playing Black: 458 - 1151 - 941  [0.364] 2550
...      White vs Black: 2211 - 966 - 1925  [0.622] 5102
Elo difference: -9.6 +/- 7.5, LOS: 0.6 %, DrawRatio: 37.7 %
SPRT: llr -2.26 (-78.3%), lbound -2.25, ubound 2.89 - H0 was accepted

Tuning each rank:

Test  | eval/protected-pawns
Elo   | -7.84 +- 6.23 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | -2.25 (-2.25, 2.89) [0.00, 3.00]
Games | 7534: +2294 -2464 =2776
Penta | [336, 884, 1442, 824, 281]
https://openbench.lynx-chess.com/test/314/