do not export component classes

Author: xkam

js/datagrid.js

@@ -3,4 +3,4 @@ import {build} from './framework.js';
 import * as components from '@activewidgets/datagrid/js';
 import * as metadata from '@activewidgets/datagrid/metadata';
 
-export const {Datagrid, Row, Gridview, Scrollbars} = build(components, metadata);
+build(components, metadata);