We add the flake8 configuration used so we ensure everyone uses the same.
We remove the usage of __all__ for non public API.
When possible, we rationalize the class name according to its __name__ and module.
issue9082
review297061002
Each time the order is reset to draft, we increase the revision number.
The order, lines and tax lines are also historized to browse past version.
issue8366
review279381002