fix bug with DNA codec usage

Link: https://github.com/GeneAssembly/biosal/issues/527
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
get connectivity

Link: https://github.com/GeneAssembly/biosal/issues/527
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>