Program to convert craters stored as polygons in a shapefile to a .diam file
that is readable by the IDL program craterstats.

USAGE:

  shp2diam [FILENAME]

Where FILENAME is the path to the shapefile.
    
If the following columns are present in any combination of character case 
the program will include them in the output file:

    diameter|diam|d
    radius|rad|r
    latitude|lat
    longitude|lon