Missing dict entries for some be/rx combos in plot_utils

[tcromartie]

We just need to add entries for all backend/receiver combos for markers and colors in plot_utils.py... easy fix but requires attention to make it look good and readable. Awful temporary fix starting at line 361 and 2093:

        # Get plot preferences
        if 'fmt' in kwargs.keys():
            mkr = kwargs['fmt']
        else:
            try:
                mkr = markers[r_b_label]
                if restype == 'both':
                    mkr_pre = '.'
            except:
                mkr = 'x'
                log.log(1, "Rec/Bknd combo doesn't have a marker label!!")
        if 'color' in kwargs.keys():
            clr = kwargs['color']
        else:
            try:
                clr = colorscheme[r_b_label]
            except:
                clr = 'k'
                log.log(1, "Rec/Bknd combo doesn't have a color!!")

[gooddc]

I knew about this -- I keep finding new fe/be pairs, but fortunately we have more finalized data now so we should be able to finish the list.

After that, we may want to think about making the markers/colors meaningful -- there's so many that it's tricky.

[rossjjennings]

The IPTA side of this was largely addressed by #54, which introduced the IPTA color scheme. But the VEGAS color schemes are a separate issue (#33).