implement Beeswarm Plots

[bothness]

Two related requests.

First, it would be fantastic to have a beeswarm plot functionality in D3plus. It is the one chart type that I use regularly that is not included at the moment.

Second, if the above is doable, it would be fantastic to make the beeswarm plot part of the existing scatter chart, whereby removing the y accessor key/function would plot the x values as a beeswarm. This would make it possible to transition/animate between a scatter and a beeswarm plot.

Below is an example that I coded in Svelte for a project, which unfortunately I don't think I'm capable of replicating within the D3plus framework. (Live version here)