Graphics improvements

[tobydriscoll]

1. Move infinity to the south pole on the Riemann sphere (a la Wegert).
2. Use a variant of Wegert's function explorer.
3. Create a point/click grid generator.

[ehkropf]

Can't disagree with 1).

What did you have in mind for 2)? It's not clear to me what part of Wegert's function explorer is applicable to what we're doing. Unless you're thinking of allowing typing the map command line constructors into a text dialog. I guess that would be like Wegert's explorer.

Could you please expand on 3)?