Replace (rtype, return) by returns

modules/plugin_dbui/converter.py

modules/plugin_dbui/dbsvc.py

modules/plugin_dbui/directsvc.py

modules/plugin_dbui/extjs.py

modules/plugin_dbui/filters.py

modules/plugin_dbui/helper.py

modules/plugin_dbui/mapper.py

modules/plugin_dbui/navtree.py

modules/plugin_dbui/selector.py