Issues with globe=True

[lukelbd]

globe=True doesn't work anymore for me with contourf after this (or maybe before this? I'm not sure). But it fixes the seam on pcolormesh but not contourf right now. I had to manually run the cartopy add_cyclic_point.

I'm not sure how to reproduce this with simple data. It's always a mystery to me which data makes a seam.

Originally posted by @bradyrx in #58 (comment)

[lukelbd]

@bradyrx Commit 077e1ab repairs this. This had to do with the order in which transform_wrapper was being applied. The existing approach for applying "wrappers" is really tricky for debugging / development; definitely points to the need for completing #45.