message: Cache 'k','i','s' for rooms
diff: @@ -866,6 +866,9 @@ IrcHandler.prototype._onPrivateMode = Promise.coroutine(function*(req, server, c
  }
  const key = this.ircBridge.publicitySyncer.getIRCVisMapKey(server.getNetworkId(), channel);
  + matrixRooms.map((room) => {
  + this.ircBridge.getStore().setModeForRoom(room.getId(), "s", enabled);
  + });
  // Update the visibility for all rooms connected to this channel
  return this.ircBridge.publicitySyncer.updateVisibilityMap(
  true, key, enabled
  @@ -880,6 +883,7 @@ IrcHandler.prototype._onPrivateMode = Promise.coroutine(function*(req, server, c
  "Reverting %s back to default join_rule"),
  room.getId()
  );
  + this.ircBridge.getStore().setModeForRoom(room.getId(), mode, enabled);
  if (enabled) {
  return this._setMatrixRoomAsInviteOnly(room, true);
  }
  