[CWEP002] properly handle serialization of computed attributes Until this cset, only serialization of computed attribute's formula was handled (thanks to the relation definition's properties dict). We now: * properly serialize/deserialize attribute's formula * test first if the database has been migrated and contains related column or not Related to #3546717

[CWEP002] Add support for computed attribute synchronization Related to #3546717. Test and handle the behaviour with several formulas and identified use cases. To do so add a birth year and a computed attribute age to Person in the test schema.