This makes NUTS labels and levels to be stored in the res.country object.
Now creating l10n submodules is a piece of cake!
Relational fields now follow guidelines on naming. Old name attribute used
for backwards compatibility wherever needed.
Also some methods have been renamed, and refactored to be smarter. Most cases
l10n modules will just need to fill the res.contry table, and regions and
substates domains will work out of the box. In case you still need to
overwrite any method, splitting in smaller methods makes it easier too.
Oh! And no need for recursive dictionary updates.
Return dict() to make it easier for submodules to add domains.
Fix KeyError: 'substate_id_level'.
Jairo Llopis