auto relogin when account name is changed
it is similar to #1551 (closed). Now we just show an error dialog, saying that user should not be connected.
Having the fact that when we create a new account, it iss given the name of the server, one of the first things that user will do is to change this name to his real name. At least this is what I do first.
Sever name is not that important, especially when only one account is in use, but this is a different ticket.