New IUGONET features

[jameswilburlewis]

Yoshi M. told me that there is new support for additional ground-based data source (some cameras, I think?). We should incorporate this in SPEDAS and PySPEDAS.

[jameswilburlewis]

github.com/iugonet/pyudas

The iugonet plugin in IDL SPEDAS was last updated Oct 29, 2021. There are a few commits later than that in the above repo.
Probably we should just unpack the whole subdirectory over the existing code, then commit any changes (and check for file deletions).

Then we can think about porting iugonet to pyspedas.

It seems there is some duplication of routines between iugonet and erg (e.g. erg_load_gmag_mm210.pro and iug_load_gmag_mm210.pro). But iugonet has many more routines than erg/ground.