Python 2 is very near end-of-life, and Python3-compatible changes to a
few scripts introduced compatibility problems with 2.7 again. It went
unnoticed for me since my system symlinks "python" to "python3", but
it broke the build on systems where that symlink is still python2. At
this point in time, I feel it is worth targetting modern Python and
forgetting about 2.7.
Using the black code reformatter, pass it over all our Python files.
This allows for a consistent style across the code base.
Exception: lumps/dmxgus/stats.py, for readability.
