support multigroup
This is a draft PR for multigroup support
@shbrief don't forget this PR!
@LiNk-NY Is this pull request ready to be merged?
@shbrief Not yet, the plots have to be updated so that there are multiple panels of pairwise comparisons, IIRC.
@LiNk-NY Got it. Yeah, I was wondering how the plotting will be affected by multiple classes. :)
@sdgamboa (and maybe @asyakhl ?) would you take a look at this PR and think about the plotting of multiple classes? I think it would just mean multiple pairwise classic LEfSe plots.
@asyakhl reminder of this pull request to review.