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
We add a selection field on price list to define how to get the unit.
But also we remove the digits constraint on the quantity as it is compared
against an non-rounded value.
issue8442
review255621002
Cédric Krier