Do some level of local echo for widgets

* Show a spinner while we wait for widgets to be deleted
 * Hide widgets while they're pending deletion
 * Don't put another jitsi widget into the room if there's already
   one pending

src/actions/MatrixActionCreators.js

@@ -183,6 +183,20 @@ function createEventDecryptedAction(matrixClient, event) {
     return { action: 'MatrixActions.Event.decrypted', event };
 }
 
+/**
+ * Create a MatrixActions.RoomState.vents action that represents
+ * a MatrixClient `RoomState.events` matrix event, emitted when the
+ * state events in a room change.
+ *
+ * @param {MatrixClient} matrixClient the matrix client.
+ * @param {MatrixEvent} event matrix event which caused this event to fire.
+ * @param {RoomState} state room state whose RoomState.events dictionary was updated.
+ * @returns {EventDecryptedAction} an action of type `MatrixActions.Event.decrypted`.
+ */
+function createRoomStateEventsAction(matrixClient, event, state) {
+    return { action: 'MatrixActions.RoomState.events', event, state };
+}
+
 /**
  * This object is responsible for dispatching actions when certain events are emitted by
  * the given MatrixClient.
@@ -204,6 +218,7 @@ export default {
         this._addMatrixClientListener(matrixClient, 'Room.timeline', createRoomTimelineAction);
         this._addMatrixClientListener(matrixClient, 'RoomMember.membership', createRoomMembershipAction);
         this._addMatrixClientListener(matrixClient, 'Event.decrypted', createEventDecryptedAction);
+        this._addMatrixClientListener(matrixClient, 'RoomState.events', createRoomStateEventsAction);
     },
 
     /**