kill foreach opApply iteration (too slow)
actually there could be interior pointers once string cache is out of scope
add rehashing and simpler hash-table (sadly too slow)
actually use the power-of-two assumption, brings it on par with load factor of 0.5
a bit of tuning and it beats fixed-sized table by very slim margin
Merge pull request #34 from blackwhale/more-mojo

More flexible hash table with rehashing