PyAnalysisUtils: Python 3 / flake8 fixes
Updates to work with python 3. Enable flake8 checking and fix warnings.
Also re-enable the unit tests, which were disabled probably during the move to cmake, and get them working again.
Updates to work with python 3. Enable flake8 checking and fix warnings.
Also re-enable the unit tests, which were disabled probably during the move to cmake, and get them working again.