- need to add ``unalternates''

- thread sorting needs to be improved so it doesn't need to resort all
messages when a new message arrives

- add secondary sorting support
	sort <primary-method> [ <secondary-method> ]

- add a command line option to allow headers to be included in the input when
using batch mode.

- allow reverse-* sorting with the `threads' option

- trim the size of the References: field to ``N'' message-ids when sending mail

- the search command needs some work to know when to invalidate its saved
  bit vector

- update bad content-length fields in messages

- allow access to attachments inside of a PGP encrypted message

- make the string history routines generic to allow for different classes of
  history

- attachments should be editable and viewable from the send-attach-menu
