about: GPL 3 is actually used instead of 2

lib/about.js

@@ -8,7 +8,7 @@ define(function () {
       s += "<p>Mit Doppelklick und Shift+Doppelklick kann man in der Karte "
       s += "auch zoomen.</p>"
 
-      s += "<h3>GPL 2</h3>"
+      s += "<h3>GPL 3</h3>"
 
       s += "<p>Copyright (C) Nils Schneider</p>"
       s += "<p>This program is free software: you can redistribute it and/or "