Add scale factor based on pawns

[TheRealGioviok]

Uses Weiss formula. It is non tunable at the moment.

Passed STC:

Test  | nontunable_scalefactor
Elo   | 8.45 +- 4.17 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=16MB
LLR   | 2.97 (-2.94, 2.94) [0.00, 3.00]
Games | N: 9336 W: 2531 L: 2304 D: 4501
Penta | [94, 1076, 2170, 1165, 163]

https://ob.cwchess.org/test/1397/

Passed LTC:

Test  | nontunable_scalefactor
Elo   | 12.10 +- 4.82 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 2.98 (-2.94, 2.94) [0.00, 3.00]
Games | N: 5600 W: 1495 L: 1300 D: 2805
Penta | [16, 598, 1406, 735, 45]

https://ob.cwchess.org/test/1398/

Bench: 16041361