Label offsets

[fedarko]

There are a few cases where showing a contig label "above" but outside of a contig's box could be useful:

• Contig names are really long (I've observed this in jumboDBG output)
• We're working with a small section of a graph where we want to highlight contig labels / color contigs (e.g. Figure 9B–D of the Binnacle paper)

This is controllable with cytoscape.js -- see here. Boils down to exposing a UI element. Not sure if we'd need to redraw the graph in order for the change to take effect or not, but it should at least be possible.