so, for some successful testing it seems like we need viennarna, still. That is not yet in the distribution. If truly dependending on it then bcbio ends up in contrib.
seqcluster redistributes a "Free as in beer" graph library in its source tree at ./misc/js/amcharts.js that upstream accepts to be substituted with references to the online location in a CDN. Steffen will address that. Downside of it all: seqcluster needs to go to contrib.
Additional requirements:
python3-dateutils (not yet packaged)
python3-pytz (not yet packaged)
And there are R packages that should be recommended at least (from https://github.com/lpantano/seqcluster/blob/master/scripts/install_libraries.R)