* gnus-srvr.el (gnus-server-insert-server-line): The server names

	* gnus-srvr.el (gnus-server-insert-server-line): The server names
	used in gnus-agent are different (for example, the native server
	uses the alias "native") from the names in gnus-srvr.
	Compensating by adding a second text property storing the name
	expected by gnus-agent.
	(gnus-server-named-server): New function.
	* gnus-agent.el (gnus-agent-remove-server, gnus-agent-add-server):
	No longer expect an argument as it was ignored anyway.  Uses the
	new gnus-server-named-server function to get gnus-agent compatible
	names from the server buffer.