[css] add the entypo font as available ressource (closes #2930356) This provides a standard set of pictograms for use in CubicWeb and cubes. To use a pictogram, the "cubicweb.pictograms.css" must be explicitly loaded (using, e.g. view.add_css(...)).

drop_relation_definition('CWSourceSchemaConfig', 'cw_schema', 'CWAttribute')
sync_schema_props_perms('cw_schema')