Rewrite pawn shield and storm code

Passes quickly both short TC:
LLR: 2.95 (-2.94,2.94)
Total: 5755 W: 1349 L: 1222 D: 3184

And long TC:
LLR: 2.95 (-2.94,2.94)
Total: 2744 W: 628 L: 505 D: 1611

bench: 4727133
Merge branch 'master' of https://github.com/mcostalba/Stockfish