Log Message:
Update mail/courier-imap to 4.0.6.  Changes from version 4.0.4 include:

	* Use PCRE for pattern-matching.

	* When autopurging messages from a folder based on their
	  timestamp, scan 'new' in addition to 'cur', otherwise mail
	  delivered to the folder directly never gets purged, unless
	  the folder is open.

	* Fix handling of invalid sequence number of 0.

	* NOT operator on content searches.