first attempt Transposition tables

- copy transposition table related changes from perft_cpu
- add transposition table support for the serial recursive driver kernel
and to the single-level launching kernel.
- some speed improvement vs no hash at higher depths. Most of the speed
improvement is lost because launching a single ply is very very
in-efficient :-/
- Need to think about ways to efficiently use hash tables when multiple
ply's are processed in a single kernel launch.