[transaction] explicit Transaction cnxset attribute
The Transaction object have a lot more attribute that those previously declared
in __init__. They are just dynamically assigned in Session code.
This changeset explicit the ``cnxset`` and ``mode`` attribute declaration.
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)