Print method idea: tidy lists

[zachary-foster]

Currently, print lists in taxmap print outs look like this:

<Taxmap>
  174 taxa: ab. Root, ac. Proteobacteria, ad. Bacteroidetes ... gq. Collinsella, gr. Blautia, gs. Clostridium
  174 edges: NA->ab, ab->ac, ab->ad, ab->ae, ab->af, ab->ag, ab->ah ... dj->gn, bu->go, dk->gp, cm->gq, cf->gr, cw->gs
  6 data sets:
    aes: a list of 11 items with names:
       node_size, edge_size, node_label_size, edge_label_size ... edge_label_color, tree_label_color, tree_color

It would be nice to see whats in those list items, but it would print a lot of text in many cases. It would be nice to have a analog of the tibble for lists, in which all the details/summaries are printed recursively until a specific amount of screen is used. This would be useful in general, no just for taxa.