chfi/gfaestus: a pangenome graph browser

gfaestus is a pangenome graph browser for GFA files. It reads graphs in GFAv1 format, with 2D layouts produced by odgi. The user can interact with the graph nodes, to view the set of paths at each node, or provide overlays which color the nodes based on path depth or sequence features. gfaestus can scale to simultaneously display all the nodes in a whole human pan-chromosome. To link biological features to the graph model, gfaestus uses colors and labels to display path-relative annotations provided in BED format.