akpetty/NESOSIM: Version 1.1

This latest version of NESOSIM (v1.1) includes a few minor updates/fixes to the original (v1.0) code repository. Thanks to Alex Cabaj for assistance with introducing and testing some of these items. Changes include:

Upgrade to Python 3. Switched from Basemap to pyproj/cartopy (surprisingly painful). An extended Arctic domain to cover all the southern peripheral seas. Introduction of CloudSat scaling parameters by Alex Cabaj (Cabaj et al., 2020). New wind-atmosphere blowing snow loss term (similar to lead loss but not concentration dependent). New Gaussian smoothing filter (using the AstroPy library) to reduce noise in the dynamics budgets. Replaced masked arrays with NaNs to be consistent throughout. Improved performance along coastlines. Various small bug fixes.