* Replace SSW with a custom Needleman-Wunsch like non-gapped aligner. This improves performance 3x since 90% of the time is spent in SSW and a read should align in an ungapped manner against at least one of the possible paths.
 * Fix an off-by-one bug in bam2kmer. This bug is only triggered when a kstring_t's non-zero-terminated length is equal to its maximal length.