Code Cleanup

[Eric Harper]

There is a lot of cruft left in freud, including (and to be updated):

1. Variable/method/class naming convention mismatch
2. Unused import/includes

[Bradley Dice]

@vramasub and I plan to overhaul the above-mentioned cruft in the near future.

[Bradley Dice]

We've done a lot of work on cleanup. Removing this issue because most of the remaining changes are more specific.