modified add_theme to color plots with nmfspalette

[sbreitbart-NOAA]

In my testing, adding

  nmfspalette::scale_color_nmfs() +
  nmfspalette::scale_fill_nmfs() 

to the existing plot code worked out fine, regardless of whether the plot is a scatterplot, line plot, etc. But this may fail with other types of plots.

[Schiano-NOAA]

This looks good now that the remote has been added. Please remove the extrafont package in the DECRIPTION in line 25 and then run devtools::document() in your console then commit those changes. Then go ahead with merging