* gnus-agent.el (gnus-agent-write-active): Added option of

	* gnus-agent.el (gnus-agent-write-active): Added option of
	replacing, rather than updating, the agent's active file.  Do NOT
	use the fully qualified group name as gnus-active-to-gnus-format
	blindly prefixes group names with server names.
	(gnus-agent-save-group-info): Merge BOTH min/max of current active
	range, was just merging min, with specified active range.
	(gnus-agent-expire): Save agent's active ranges after
	expiring all groups.
	(gnus-agent-expire-group-1): Update min of agent's active range to
	min article currently fetched.
	(gnus-agent-expire-unagentized-dirs): Avoid asking to delete the
	same ancestor multiple times.