* camel-mime-message.[ch]: Remove the "session" field from
	CamelMimeMessage. Nothing uses it, about half of the existing
	calls to camel_mime_message_new_with_session pass NULL, and
	there's no obvious reason for it to be there.

	* others: Use camel_mime_message_new instead of
	camel_mime_message_new_with_session

svn path=/trunk/; revision=2479