setup.py: enable pytest-sugar plugin pytest-sugar enables a nice visual representation of test progress and results. Minimum version is set to 0.7.0 as it fixes a problem where skipped tests would not be shown in the test summary. The upper version 1.0.0 is arbitrarily chosen and could be increased as seen fit.

# 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
.