German "Umlaute" in tags are not converted to lowercase correctly

When entering an uppercase character as a marker, it will be converted lowercase automatically. However, this does not function for german "Umlaute", that it "Ü", "Ö" and "Ä". Because of this, entries marked with such a tag won't be found. Solution: convert uppercase Umlaute to lowercase. http://cintanotes.com/forum/viewtopic.php?f=6&t=1090