New moderator app WIP:

* #144: moderator notes WIP,
* plugin size: adding an API,
* refactoring the code from the task app, to create a new MUC App
  system.

conversejs/custom/templates/muc-chatarea.js

@@ -13,5 +13,10 @@ export default (o) => {
         ? html`<livechat-converse-muc-task-app .model=${o.model}></livechat-converse-muc-task-app>`
         : ''
     }
+    ${
+      o?.model && api.settings.get('livechat_note_app_enabled')
+        ? html`<livechat-converse-muc-note-app .model=${o.model}></livechat-converse-muc-note-app>`
+        : ''
+    }
     ${tplMUCChatarea(o)}`
 }