dsk 1.6066: New formula

DSK is a k-mer counting software, similar to Jellyfish. Jellyfish is
very fast but limited to large-memory servers and k ≤ 32. In contrast,
DSK supports large values of k, and runs with (almost-)arbitrarily low
memory usage and reasonably low temporary disk usage. DSK can count
k-mers of large Illumina datasets on laptops and desktop computers.