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.