Add "map" of assembly graph's connected components

[fedarko]

We want to be able to distinguish assemblies with lots of tiny components (e.g. biofilm 2) vs. asms with a few large components (e.g. shakya old, biofilm 1). Basically, ways to represent how "noisy" certain components are.

[fedarko]

I was thinking we could use a Treemap or something similar for this? where each component is a section that is scaled by total number of elements, or something. If we do this using d3 then we could include the functionality for the user to order components by, say, number of bubbles, number of edges, etc.

[fedarko]

Now that we're officially using d3.js (due to #232), displaying a treemap shouldn't be that difficult. (An example of this functionality is given here.)

Once we have treemap display functionality ready, selecting a connected component in the treemap would just draw that particular connected component (I guess we could do standard mode by default, although modifying it to draw SPQR mode connected components instead would also be doable).

Another cool thing here is that we could let the user choose what attributes to use for the "size" of each connected component's corresponding rectangle in the treemap: I'd imagine the default would just be number of contigs (analogous to how the current ordering of connected components by "size" works), but we could also provide number of edges, number of bubbles, etc. as various attributes that would set connected components' size in the treemap.

For the sizing stuff, we could even go nuts with this and let the user design their own metric composed of these attributes (e.g. ccSize = sum(node count, 0.5 * edge count, 2 * bubble count, cyclic chain count) or something like that), in which certain attributes can be weighted more or less. However, just drawing a simple treemap based on node size would definitely be a good starting point here.

[fedarko]

An idea: selecting a cc in the treemap opens up a "component info" dialog or control panel section, and the user can then choose whether or not to draw the cc in question.

[fedarko]

This issue was moved to marbl/MetagenomeScope#35