LMR: do shallower

[eduherminio]

Test  | do-shallower
Elo   | 2.40 +- 1.86 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=16MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 3.00]
Games | N: 45022 W: 11164 L: 10853 D: 23005
Penta | [482, 5431, 10441, 5608, 549]

https://ob.cwchess.org/test/1154/

[WIP]

Test  | do-shallower
Elo   | 1.74 +- 1.83 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 1.74 (-2.94, 2.94) [0.00, 3.00]
Games | N: 39444 W: 9304 L: 9106 D: 21034
Penta | [182, 4721, 9781, 4793, 245]

https://ob.cwchess.org/test/1183/

Bench: 17181773