new name
TrendVis should get a better, more accurate name. Suggestions welcome!
multiscales? stacks? multivariables? axis_family? It is related to the existing axes_grid and axes_grid1, but I don't think we want it to be "axes_grid2". At the moment, among the quick thoughts above, I think I like "axis_family" (or "axes_family") best, because the package seems to me to be about working with multiple axes with varying degrees of relationship.
How about staxes - or is that too cutesie? Project looks great, btw, @mscross - congrats and thanks for putting this together!
(pronounced "stack-sies")
Maybe leave off the "es" -> "stax".
I vote for staxes, but stax is also cool.