Improve the schema command with filtering option.
meta data and workflow data are hidden by default. show-meta and show-workflow
option are added to display them. Another "hide-type" option allow to hide
additional entities type.
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)