support `setup_requires` in setup.cfg

python 3 bdist_egg --exclude-source-files __pycache__ issue

Include license file in the generated wheel package

The wheel package format supports including the license file. This is
done using the [metadata] section in the setup.cfg file. For additional
information on this feature, see:

https://wheel.readthedocs.io/en/stable/index.html#including-the-license-in-the-generated-wheel-file

commands: dist_info: say something!

The dist_info command did not say anything like other
commands did. This gives some more helpful information.