cleanup: run pyflakes as a part of scripts/run-all-cleanup pyflakes has no usable configuration options, so create a small wrapper script. Instead of having two wrapper scripts (with one being almost nothing and the other containing configuration), just keep it simple and use one combined.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.