message: Handle/hide old rooms in the room list
  Fixes
diff: @@ -181,6 +181,12 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
  const room = this.matrixClient.getRoom(roomId);
  const tryUpdate = async (updatedRoom: Room) => {
  console.log(`[RoomListDebug] Live timeline event ${eventPayload.event.getId()} in ${updatedRoom.roomId}`);
  + if (eventPayload.event.getType() === 'm.room.tombstone' && eventPayload.event.getStateKey() === '') {
  + console.log(`[RoomListDebug] Got tombstone event - regenerating room list`);
  + // TODO: We could probably be smarter about this
  + await this.regenerateAllLists();
  + return; // don't pass the update down - we will have already handled it in the regen
  + }
  await this.handleRoomUpdate(updatedRoom, RoomUpdateCause.Timeline);
  };
  if (!room) {
  @@ -334,7 +340,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
  }
  await this.algorithm.populateTags(sorts, orders);
  - await this.algorithm.setKnownRooms(this.matrixClient.getRooms());
  + await this.algorithm.setKnownRooms(this.matrixClient.getVisibleRooms());
  this.initialListsGenerated = true;
  