Comment by quietbritishjim

To answer my own questions:

* Yes it seems ProPlot stagnated and no longer works with latest matplotlib versions. UltraPlot is a fork that fixes that:

https://github.com/proplot-dev/proplot/pull/459

* Yes, the documentation says that GeoAxes is from Cartopy.

(Also, typo: the project description says "succint" rather than "succinct".)