Added additional data fields to superdarn_radars.py

[DannoPeters]

geographic: Named Tuple containing geographic latitude longitude and boresight
geomagnetic: Named Tuple containing geomagnetic latitude longitude and boresight
decommissioned: date radar was decommissioned (shut down)
commissioned: date radar was officially commissioned (data considered stable)
beamSep: angular separation between radar beams

[aburrell]

Regardless of whether we go forward with my suggestion, the docstring and variables should match.

[mts299]

Moving merge to develop since we don't have plotting/rtp anymore. I would like to also use this for my summary generation plots.

[mts299]

Will test this tomorrow, just cleaned up the file to meet PEP8 standards.
If @aburrell if you are good with my suggestion on altitude then I will merge it tomorrow after my testing.

I would like to move this to develop ASAP so I can use it in my summary plot generation scripts.

[mts299]

Did this test in the python interpreter:

python 
Python 3.6.9 (default, Oct 29 2019, 10:39:36) [GCC] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pydarn 
>>> pydarn.SuperDARNRadars
<class 'pydarn.plotting.superdarn_radars.SuperDARNRadars'>
>>> pydarn.SuperDARNRadars.radars[65]
_Radar(name='Rankin Inlet', stid=65, abbrev='rkn', beams=16, gates=100, geographic=_Coord(lat=59.6, lon=-64.3, bore=-16.2), geomagnetic=_Coord(lat=72.6, lon=-26.4, bore=1.8), hemisphere=<_Hemisphere.North: 1>, institute='University of Saskatchewan', decommissioned=None, commissioned=datetime.datetime(2007, 5, 1, 0, 0), beamSep=3.24)
>>> pydarn.SuperDARNRadars.radars[65].beams
16
>>> pydarn.SuperDARNRadars.radars[65].geographic
_Coord(lat=59.6, lon=-64.3, bore=-16.2)
>>> pydarn.SuperDARNRadars.radars[65].hemisphere
<_Hemisphere.North: 1>
>>> pydarn.SuperDARNRadars.radars[12].hemisphere
<_Hemisphere.South: -1>
>>> pydarn.SuperDARNRadars.radars[12].name
'Syowa South'

[mts299]

Merging code, and will be making an issue on adding the altitude to this file for the future.