Add some typing information, or make it consistent.
 Add more docstrings.
 Fix using Skip in switch converter.

 Use ©

In the process:
* Update based on latest xcg/templates/odoo_module.
* Fix existing MailTemplate converter (found by these new tests).

Fix issue with Switch and the use of Skip as a converter, also make switch send Skip when nothing matches its rules.

Fix issue with RelationToMany that always convert to Skip when send_empty is False.

Fix issue with chaining relation converter with empty values.

update to use latest template, using | instead of Union as allowed by python 3.10 as it is more readable

 avoid legacy converters in tests, add warnings on deprecation, include the functionnality of FirstKeyField in KeyField

See ``tests/test_relation.py > test_many2one_to_odoo`` for a test case.

``get_instance`` functions can now return a ``Newinstance`` record (record being created).

 Add tests, correct code so test passes.
Fix issues with some converter.

Split converters in multiple modules
Remove deprecated converters
Move legacy converters in a dedicated module