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.

if repo.system_source.dbdriver == 'postgres':
    sql('ALTER TABLE appears ADD COLUMN weight float')
    sql('UPDATE appears SET weight=1.0 ')