change TimelineWindow to take a timelineSet rather than a Room

lib/models/room.js

@@ -244,6 +244,20 @@ Room.prototype._fixUpLegacyTimelineFields = function() {
     this.currentState = this._timelineSets[0].getLiveTimeline().getState(EventTimeline.FORWARDS);
 };
 
+/**
+ * Return the timeline sets for this room
+ */
+Room.prototype.getTimelineSets = function() {
+    return this._timelineSets;
+};
+
+/**
+ * Return the notification timeline set for this room
+ */
+Room.prototype.getNotifTimelineSet = function() {
+    return this._notifTimelineSet;
+};
+
 /**
  * Get the timeline which contains the given event from the unfiltered set, if any
  *