Activate first menu item if first cat is headless

lib/services/menu.service.ts

@@ -200,6 +200,9 @@ export class MenuService {
 
   setActiveByHash(hash) {
     if (!hash) {
+      if (this.categories[0].headless) {
+        this.activate(0, 0);
+      }
       return;
     }
     let catIdx, methodIdx;

lib/services/schema-helper.service.ts

@@ -28,6 +28,7 @@ export interface MenuCategory {
   empty?: string;
   virtual?: boolean;
   ready: boolean;
+  headless: boolean;
 }
 
 // global var for this module