Doh. Don't remove things from the hash table while foreach'ing it. (And

Doh. Don't remove things from the hash table while foreach'ing it. (And

	* providers/imap/camel-imap-message-cache.c
	(camel_imap_message_cache_clear): Doh. Don't remove things from
	the hash table while foreach'ing it. (And can't use foreach_remove
	either because we have to remove them in a weird order). Fixes
	#3618.

	* providers/imap/camel-imap-folder.c (imap_get_message): If the
	server returns OK from the FETCH BODY, but there's no parseable
	BODY response, it's probably because there's an UN-parseable BODY
	response, implying the message is badly formatted, MIMEwise. In
	that case, fall back to fetching the message as a single part.