Provide type hints and add static type checking

[sbrugman]

Add type hints to as code documentation, IDE hints and possibly catching errors. Add flake8-annotations to pre-commit and enable mypy in CI.

[sbrugman]

Cool project that could kickstart this issue:
https://zenodo.org/record/5151994
https://pypi.org/project/typing-copilot/

[sbrugman]

Used https://github.com/JelleZijlstra/autotyping in #262