Task lists WIP:

* initializing some code parts
* mechanism to add font-awesome icons to the defaults one that
  ConverseJS uses
* new way to override ConverseJS index.js (to add new custom plugins,
  that are directly build into ConverseJS)

conversejs/custom/plugins/tasks/task-list.js

@@ -0,0 +1,15 @@
+import { Model } from '@converse/skeletor/src/model.js'
+
+/**
+ * A chat room task list.
+ * @class
+ * @namespace _converse.ChatRoomTaskList
+ * @memberof _converse
+ */
+class ChatRoomTaskList extends Model {
+
+}
+
+export {
+  ChatRoomTaskList
+}