Support 3D plotting through interface to e.g. GeoVista

[sadielbartholomew]

At present, cf-plot only supports two-dimensional plotting, by means of interfacing with the Cartopy and matplotlib libraries.

However, as a long-term goal, a feature that would be really useful to users would be to also support 3D plotting. This would be very time-consuming and complex to develop from scratch, but if we interface with libraries which support 3D cartographic plots, this can do the heavy lifting, and as with the 2D case we then provide an interface on top of that to handle metadata considerations and such and consolidate the set-up using our own API.

Such a library that looks very promising in this respect is GeoVista. It looks like it is still under-development (pre-v1.0 and placeholder docs) but once this looks more mature we should get in touch with the developers to investigate ways forward towards the goal of supporting 3D plotting. There may also be other libraries that would work, so we should explore the ecosystem for anything relevant.