Standard Colormaps for common variables

[kevindougherty-noaa]

In order to keep consistency among figures, there should be standard color maps implemented in emcpy.

I found the following color maps from a former colleague (https://github.com/blaylockbk/pyBKB_v3/blob/master/BB_cmap/NWS_standard_cmap.py). A source comes from a PDF that was saved among our research group. I would need to verify if these are still the correct colormaps, but I find it appropriate to use NWS colormaps if possible.

Here are the colormaps plotted between their max and min values:

[kevindougherty-noaa]

Just a note: The precipitation plot is not normalized correctly.