Introduce attacks on space area
This patch introduces a small malus for every square in our space mask
that is attacked by enemy. The value of the malus is completely arbitrary
and is something we can tweak, also maybe we can gain some elo with tweaking
space threshold after this addition.
Passed STC
http://tests.stockfishchess.org/tests/view/5d10ce590ebc5925cf0af30b
LLR: 2.96 (-2.94,2.94) [0.50,4.50]
Total: 7082 W: 1648 L: 1449 D: 3985
Passed LTC
http://tests.stockfishchess.org/tests/view/5d10d2d80ebc5925cf0af3fd
LLR: 2.96 (-2.94,2.94) [0.00,3.50]
Total: 79494 W: 13727 L: 13324 D: 52443
Closes https://github.com/official-stockfish/Stockfish/pull/2207
bench 3516460