unique_together integration in CW (alf+syt)
* added in-DB representation of the constraint with a new entity type (CWUniqueTogetherConstraint)
* the schema is now migrated on a sync_schema_props_perms(EType) call in the migration script
* removed the migration commands provided in the first implementation
add_relation_type('prefered_form')
rql('SET X prefered_form Y WHERE Y canonical TRUE, X identical_to Y')
commit()
drop_attribute('EmailAddress', 'canonical')
drop_relation_definition('EmailAddress', 'identical_to', 'EmailAddress')
if 'see_also' in schema:
sync_schema_props_perms('see_also', syncprops=False, syncrdefs=False)