hamming_bitwise: Fast Bitwise Hamming Distance Vector Computation
Description
Takes in a binary matrix \(\mathbf{X}\), whose transpose \(\mathbf{X}^T\)
has \(N\) rows, and computes a vector recording all
\({N \choose 2}\) pairwise Hamming distances of \(\mathbf{X}^T\),
ordered lexicographically.