remove unused constant
extend checking moves only if see >= -1 pawn
first pass at using hash table in q-search
Remove lazy eval from scoring module. Cache eval in main hashtable instead.
Restrict hashtable to be a power of 2 number of entries.
Limit max ply to 62 (so can accomodate -1 and -2 values for qsearch)
Some code cleanup.
optimize Board::between and Board::clear by using pre-computed arrays.