various widget refactorings

src/public/javascripts/widgets/link_map.js

@@ -8,7 +8,7 @@ const TPL = `
 </div>
 `;
 
-class LinkMapWidget extends CollapsibleWidget {
+export default class LinkMapWidget extends CollapsibleWidget {
     getWidgetTitle() { return "Link map"; }
 
     getHelp() {
@@ -60,6 +60,4 @@ class LinkMapWidget extends CollapsibleWidget {
             this.refresh();
         }
     }
-}
-
-export default LinkMapWidget;
+}