Currently in setup.py, we call generate_user_files.py, which requires
interactive input. This is bad for package managers like the bug
report mentions, and also for pypi/pip.

Removing it is a little more difficult for users, they need to now run
both setup.py and generate_user_files.py, but I think that's an ok
tradeoff. Most users will be using the pwb.py script anyways, so this
wouldn't even affect them.