Add support for UUIDs.

This will update Deadbolt to support UUIDs. It will put the UUIDs into an 8 character string, in most cases they will be Chinese characters. Because we don't know where a Deadbolt sign is they will only show the correct user name if they're clicked by the player first. This could be probably prevented by checking all outgoing packets or something similar but that would be pretty inefficient.

Exisiting signs are converted once they're used for the first time. If multiple user names with the same prefix over 15 characters are available then it is converted to the player that played on the server before the other ones - there is no way to check which player is the real one.