Clean up fieldsim script

[Evan Pratten]

The fieldsim script is a bit of a mess from me playing with features. Can someone clean it up, add some comments, and add a docstring to each function?

It is located at src/main/python/fieldsim/fieldsim.py

I would also like to add pylint support to the project, but this can be done later.

[Evan Pratten]

Pushing back to week 2