Optimized TranspositionTable::probe() using partial template specialization.

Optimized TranspositionTable::probe() using partial template specialization.
No loops or temporary variables and fewer instructions.

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I just realized I quite stupidly submitted this change to the test network where it marginally failed.  I forgot Gary L. has once told me that pure speed optimizations don't have to go through the test network.  I have timed this change to be 15% faster using QueryPerformanceCounter() and it is on the hot path.  Bench also runs consistently almost 2% faster overall.  The behavior is identical and there is no functional change so this can only be a gain.  I think it may only  be around 1 or 2 elo which is too small to reliably test.