Major changes, and improved testing
List of changes :
- Use of pytest and mypy in github action, and tracking of the test cover
- Mise under licence BSD-1-Clause
- Improvement of the documentation
- Addition of a tensorflow extra along with the corresponding type of imputer
- New metrics for a better estimation of the error in terms of distribution
- Several imputers have been renamed
- Implementation of 75 tests, covering 57% of the code