Implement Hamming distance

[opatiny]

The Hamming distance can typically be used to compute the distance between two bit strings very easily, by doing sum(xor(a,b)). It counts the number of dissimilar elements between the strings. It can be used as a distance measurement for feature matching.

https://en.wikipedia.org/wiki/Hamming_distance

[lpatiny]

Should get inspired by Tanimoto:
https://github.com/mljs/distance/blob/master/src/similarities/tanimoto.js
Take care than tanimoto has this flag 'bitvector' to specifiy that the a and b parameters are array (of uint32 I guess).