Start of 3D plots: Basic plot_surface

[ianhi]

Quick first pass at implementing plot_surface using the artist.remove strategy from #89 (comment)

attn: @redeboer this is a rough starting place. If you'd like to work on this you're absolutely welcome to work starting off this branch. I probably will only work on this in occasional spurts as it isn't a pressing need for me. So if you aren't able to work on this but it's something you'd like to be able to use then I'd also be open to releasing it before I clean up having all the arguments be callable and other polish.

One thing I didn't realize previously is that we have to do some shenanigans with the color cycles in order to get the color to stay the same.

See also: t-makaro/animatplot#57 by @johnomotani

TODO:

1. This is far from perfect. In particular most of the parameters can actually be callables (https://matplotlib.org/stable/tutorials/toolkits/mplot3d.html#mpl_toolkits.mplot3d.Axes3D.plot_surface)
2. Currently if Y is a callable is must accept X as an argument. This probably shouldn't be a hard requirement.
3. Docstring!
4. Docs page?

Final thought: Rewriting the vmin_vmax code for the Nth time has me really thinking that perhaps this function approach wasn't really the best. Maybe I should have made my own artist type objects that know how to update themselves. So then there could be a HasNorm class that handles all the vmin_vmax stuff in one place.