[REF] Don't use ``product.product`` model for Reasons, because Odoo remove
the fields ``expense_pdt`` ``and income_pdt`` from the model.
Use instead a new model ``pos.move.reason`` for this purpose.
[REF] Doesn't inherit from ``cash.box.in`` and ``cash.box.out`` model,
as there are bad designed and doesn't allow clean inheritance.
Instead, use new transient model ``wizard.pos.move.reason``.
[REF] Oca convention. add readme folder.
Sylvain LE GAL