[sql] preprocess_entity uses lgdb helper's SQL converters.
The preprocess_entity does not yield anymore the conversion logic for different
base types, but relies on a new SQL_CONVERTERS dictionary of the db helper.
This will allow later inclusion of new base types.
fromcubicweb.schemas.baseimportin_group,CWSourceSchemaConfig# copy __permissions__ to avoid modifying a shared dictionaryin_group.__permissions__=in_group.__permissions__.copy()in_group.__permissions__['read']=('managers',)cw_for_source=CWSourceSchemaConfig.get_relation('cw_for_source')cw_for_source.__permissions__={'read':('managers','users'),'add':('managers',),'delete':('managers',)}