LMR: do deeper full depth search when reduced depth search is better than best_score by a big margin

[TheRealGioviok]

Passed STC

Test  | dodeeper
Elo   | 4.25 +- 2.77 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=16MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 3.00]
Games | N: 20252 W: 5117 L: 4869 D: 10266
Penta | [217, 2367, 4739, 2557, 246]

https://ob.cwchess.org/test/1148/

Passed LTC

Test  | dodeeper
Elo   | 6.91 +- 3.55 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 2.97 (-2.94, 2.94) [0.00, 3.00]
Games | N: 10412 W: 2537 L: 2330 D: 5545
Penta | [43, 1188, 2552, 1365, 58]

https://ob.cwchess.org/test/1150/

Bench: 17112715