Allow user to choose color map

[markmac99]

Changes to allow the operator to choose the color map for shower associations. Two options created

• new config entry shower_color_map in a new section [Colors]
• new parameter --palette (-p) which can be passed to both Utils.ShowerAssociation and RMS.Formats.Showers
• The value of the parameter can be any matplotlib colour. To see the options call the function with "-p help"
• I also added support for reading the config file from alternate locations.
• There was also an issue in Showers.py - when the shower has no start or end in the csv file, the module would crash.
• Aside: I like summer_r, because it distinguishes between showers pretty well.
• Samples attached using data from UK0006 from last year's perseids.

Files changed:

• RMS/Formats/Showers - read parameter from config/commandline, and pass to various functions
• Utils.ShowerAssociation - read parameter from config/commandline, and pass to various functions
• RMS.Reprocess - pass config.shower_color_map to call to ShowerAssociation so that it honours the user's selection.