add lat-=lon parsing

[ChrisBarker-NOAA]

I"ve got the code:

https://github.com/NOAA-ORR-ERD/lat_lon_parser/blob/master/lat_lon_parser/parser.py

but probably should be here, rather than yet another package.

A version is in the JS code:

https://github.com/NOAA-ORR-ERD/NUCOS/blob/master/nucos.js#L830

[ChrisBarker-NOAA]

Actually, the version in its own project is being maintained ....