Ecabc

- Build/installation now uses `pyproject.toml` instead of the deprecated `setup.py`
- Unit tests now use `pytest` instead of `unittest`
- Added GitHub workflows for PyPI publishing, unit testing
- Removed redundant stuff

The following two GIFs show the behavior of ECabc (1) before and (2) after these changes:

(1)

(2)

By changing the merging algorithm to a variable permutation algorithm and ensuring employers who have exhausted their food sources turn into scouts, the ABC avoids local minima imposed by early minimum discovery and is more flexible to variable solutions. API changes are outlined in the repository's README.

- PEP8 styling overhaul
- Logical method placement
- Added files for JOSS paper
- Updated README

* Bug fixes
* Algorithm changes
* More solid multiprocessing