Added radar plots code.

Hi Ian - I just cloned your fork of great3-public so I could try to run and play with this code, but it doesn't run for me as-is because of this line that I'm commenting on.  My version of NumPy is giving a NotImplementedError because it doesn't like that the argument is a list of strings.

If I change this line to ```data = np.ones(len(branch_list), dtype=float)``` then that works, and I think that should be okay for all reasonable numpy versions.  So i recommend making that change if you don't mind (I don't think I can push to your fork so I didn't try to commit and push it).