[Other] Some hash statistics

As you know I am currently working with the eval and pawn hash for the evaluation. With both implemented it seems Mediocre goes from around 100.000 nodes per second to about 150.000 on my hardware (AMD Athlon 2500+). This is quite promising since it is a pure speed gain, i.e. the exact same number of nodes are visited for each ply of the same position, and the end result is (should be) exactly the same (same move and same evaluation).

From the start position searched to 10 ply I get:

evalHashHits 40409
evalHashMiss 100159
pawnHashHits 126433
pawnHashMiss 14135

As expected the pawn hash hits far more often than the eval hash.

While the eval hash seems to work flawlessly the pawn hash is having some problems. Sometimes returning wrong values, this is of course not acceptable, but instead of just fixing the bug I will take a look at how the pawn evaluation is handled and adjust it to work smoothly with the pawn hash.