Markdown README is now the main one

Added a manifest.in file

See tcalmant#36
Also added a small version bump as it is a metadata-only change

Added missing packages in setup.py

Re-format with black

Version bump to 0.2.4

Updated README

Version bump: 0.2.2

 Version bump: 0.2.1

Added an "AUTHORS" file

Version bump to an upload error on PyPI