Add feedback to timestamps

Added a feedback message to users when they configue the timestamps.

js/sim.js

@@ -1126,6 +1126,7 @@ function Lobby(id, elem) {
 				timestamps.pms = targets[1];
 				break;
 			}
+			rooms.lobby.add('Timestamp preferences set to: ' + targets[1] + ' for ' + targets[0] + '.');
 			Tools.prefs.set('timestamps', timestamps, true);
 			return false;