This allows to replace time_locale and use the translation infrastructure
instead. So it can be customized using the translation override or derivative
languages.
This provides also a standard base to modules that needs calendar month and
day.
issue7815
review56451002
This is done by calling first the getter method for the parent language for the
terms that are not yet cached. After existing translations are set for the
language. And finally the result is stored in the cache.
The synchronisation wizard remove also the translations that are identical to
their parent language.
The method load_module_graph adds all parent languages to be loaded for
derivation.
issue5443
review25581002
Sebastien Marie