Setup project automations - linting, testing, doc generation etc.

[stuaxo]

pyproject.toml:

• [ ] sphinx
• [x] flake8
• [x] pytest
• [x] pytest-cov (test coverage)
• [x] black

pre-commit hook

• [x] black
• [ ] pydocstyle - check docstrings.

Initial DEVELOPER.md

• [x] linting (flake8)
• [x] formatting (black)
• [x] testing (pytest)
• [x] test coverage (pytest-cov)

see also: #7 setup project integrations

[stuaxo]

I'm going to try and setup apidoc, and have sphinx setup with markdown support instead of REST, as it seems to have more uptake than REST these days.

APIdoc with setup to use numpy style comments seems like an OK combination.

[stuaxo]

Running through this very well tooled up tutorial https://cjolowicz.github.io/posts/hypermodern-python-01-setup/

Definitely need to mention this in docs