Decrease reduction for moves that escape a capture

Passed both STC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 10094 W: 1833 L: 1704 D: 6557

and LTC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 27738 W: 4147 L: 3928 D: 19663

bench : 8599236
Add some const qualifier

No functional change.
Use see() instead of see_sign() in previous patch

Before it was working by accident in case of
see_sign() and failing with see() due to how
castle moves are coded (king captures the rook).

Better to explicitly filter out castling moves
and use see() without any surprise/trick.

No functional case.
    0.71 and 2.6 (180 elo )
cutoff for smaller than PawnValueEg differences