geom_dots_label for labeling points in geom_dots using repel

[mjskay]

Would be cool to do a text geom for labelling geom_dots based on something like ggrepel::geom_label_repel

Also might want some smart methods for selecting the points to label; e.g. strategies like: top or bottom one in a stack, convex hull, one of each unique combination of some aesthetics, plus potentially combinations of these rules, like leftmost points from each combination of some aesthetics that are on the convex hull.