WIP group colors for hclust plot

[alailink]

#408 (comment)
@kescobo

Main idea of this fork is to take the dendrogram plotting function of statsplots and color the lines by groups.
Please refer to github open issue for details.

[kescobo]

Thanks for getting this started. Excited to see where it goes 👍

[KronosTheLate]

+1 on wanting this ^_^

[kescobo]

@KronosTheLate I doubt that @alailink intends this to be cookie-licking - there's extensive discussion in the linked issue if you want to try as well / instead.

Also, @alailink if this is still of interest, offer to shepherd still stands (though I also understand if you've got other priorities).