- Removes references to 'runtests.sh', as it has been removed
- Adds links from the contributing file to the readme - testing section
- Updates flake8 stats
- Removed class definitions from `xml/__init__.pyi` as they were merely outdated duplicates of the definitions from the correct file (`xml/sax/__init__.pyi`)
- Left file intact as it is necessary for the module
- Moves the pdb stub from separate `2`/`3` files to a single file in `2and3`, as they were identical.
- Maintains the comment header, as the stub is incomplete.
- Updates documentation related to previously required comment headers.
- Removes all comment headers from stubs
- Occasionally included a header for stubs that were noted to be incomplete or contained todo's.