add option to enable codec in codec_init

Link: https://github.com/GeneAssembly/biosal/issues/273
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
only use 2-bit encoding when storing

Link: https://github.com/GeneAssembly/biosal/issues/263
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
fast ring needs only 2 padded fields, not 4

Link: https://github.com/GeneAssembly/biosal/issues/347
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
move alignment logic from kmer to hash table

Link: https://github.com/GeneAssembly/biosal/issues/350
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
align on 4 bytes

Link: https://github.com/GeneAssembly/biosal/issues/346
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>