Mmmm... This might be interesting to have, but be advised that a sort order like "A-Z" would mean that the sort order is not fixed, but heavily dependend on the language code you're using. So, the same category tree viewed in english might be sorted totally different than seeing it in german. Since I wanted fixed sort order numbers in the database to sort by, I did not provide the functionality of your proposed feature, but I will think about how to do this best.
