This release:
- adds early sanity checks about path parameters: they *must* appear as function
parameters and should not have a default value.
- path parameters converter, if declared, should be consistent with
the corresponding parameter type.
- improve `mypy` checks by removing some *ignore* hints.
- improve `Makefile`.
- rename FSA generated exceptions: `ErrorResponse` and `ConfigError`.
- add `pymarkdown` check.
- add a GitHub CI configuration (with 99% coverage for now).