--------
2020-07-05 : added functions, include stub files for typing, setup python_requires
- added python_requires in setup.py
- include type stub files, its fully type hinted package now (PEP 561)
- pep8 fix the standard library code
- added PurePath.replace_parts
- added PurePath.is_path_instance
- added Path.copy
- added Path.copy2
- added Path.copyfile
- added Path.copymode
- added Path.copystat
- added Path.copytree
- added Path.rmtree