improve verbosity

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
enable 2-bit encoding

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
fix memory leak in kmer store

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>