Add missing relation types items in schema global variables Some of these global variables are used, in particular, to control schema views (web/views/schema.py). While they are currently not properly documented (see #3360868), their definition are currently incomplete (e.g. one could reasonably expect to find ``cw_schema`` in ``SYSTEM_RTYPES``). Closes #3486114.

from datetime import datetime

for rtype in ('cw_support', 'cw_dont_cross', 'cw_may_cross'):
    drop_relation_type(rtype)

add_entity_type('CWSourceSchemaConfig')

if not 'url' in schema['CWSource'].subjrels:
    add_attribute('CWSource', 'url')
    add_attribute('CWSource', 'parser')
    add_attribute('CWSource', 'latest_retrieval')