Dramatically speedup and fix LSH's _H()
Dramatically speedup and fix LSH's _H()

The same byte result but much faster and actually always the same length.

The old approach is wrong: e.g. len("%.4x"% 741282) is 5, not 4.

arbazkhan002/datasketch,ekzhu/datasketch,chubbymaggie/datasketch,ekzhu/datasketch