------------------
- Backwards incompatible: ``json_lines.open_file`` is made private and
renamed to ``json_lines._lib._maybe_gzip_open``;
- ``json_lines.open`` now supports pathlib.Path objects;
- docstrings are added to more functions;
- logging now uses "json_lines" logger;
- logging no longer uses string formatting;
- Python 3.7 support.