Gnssrefl

Add newest L2C transmitting GPS satellite, PRN 28. Transmitting since January 31, 2023.
I do not believe it is healthy.

y-axis limits are now the same in quickLook periodograms.

Add L1C (I think) to rinex3 reading code - but it is a backup signal to default L1 C/A (S1C).
But I would really need to see more receivers to see what is going on here. They all seem to
use different settings.

Fixed persistent bugs that occur when trying to use gnssir to isolate problems with one satellite.
Now checks that the requested satellite is available on the requested frequency.
If not, it exits gracefully instead of crashing. This is when using -sat option, which is not
relevant for routine processing.

Allow capital letter station names in quickLook and gnssir (mac does not distinguish
between these two cases, but other machines do).

Explicitly check that people are not using illegal frequencies when they run gnssir

Fix bugs in nmea2snr related to how directories were created and discontinued numpy libraries

Updated snowdepth to have user-friendler bare soil definitions.

Added initial snowdepth utility.

removed np.float and np.int from gps.py library (no longer defined in newer numpy versions)

Slight changes to the behavior of refl_zones - it make a station icon and the output goes
to a subdirectory now to decrease the clutter in $REFL_CODE/Files.

Added more optional inputs to quickplt

Added Glonass to <code>nmea2snr</code>. Thank you to Daniel Nowacki for helping on this one.

Added a new utility - <code>rh_plot</code> - which is basically a way to look at RH results before you start making
products (snow, sea level, etc). It uses libraries developed for subdaily and daily_avg