Remove `long` in favor of `int`
Remove `long` in favor of `int`

The types are unified in Python 3, and `long` is no longer built-in.
The change is documented in PEP 237, "Unifying Long Integers and Integers",
https://www.python.org/dev/peps/pep-0237/

This changeset is part of a sequence that transitions TuLiP to Python 3
while maintaining support for Python 2.7.

tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control