Connected user rename

[palmer]

Simple one here.

When a player gets dropped, their ghost often shows as still logged in.
This prevents the player from reconnecting as themselves.

But after they reconnect as Bob2, the ghost frequently drops as well.

It would be nice if Bob2 could simply go

/nick Bob

And become Bob again.

- - -

Conversant to this: Using the Boot option from the Connections panel on a ghost does not actually disconnect them.