- Other than multipart/mixed and PGP/MIME, Mutt should allow the user to
  specify what to do with other types of multipart messages (i.e., so a user
  can deal with S/MIME messages reasonably)

- option to not include attachments in replies

- handle message/external-body in some fashion

- automatic POP mail checking

- read/write the .mh_sequences file?

- not possible to view the header of a single part message which contains
  something that requires a mailcap entry to view

- need to clean up the error recovery when running out of space when syncing
  a mbox/mmdf mailbox

- add tagging to the generic menu driver so that it does not need to be
  impelemented for each menu

- look at doing an insertion sort for threading so that the entire mailbox
  does not need to be rethreaded when new mail arrives

- BODY struct should probably have a pointer to its corresponding HEADER
  struct.  this is needed for mh/maildir mailboxes so the correct pathname
  can be found.  Or perhaps all we need is a .hdr member of the STATE struct
  so that all of the MIME handlers can look up the corresponding HEADERs if
  need be?

- imap debugging

- it should be possible to perform operations on attachments while viewing
  them, and be possible to go to the next or previous attachment without
  exiting the pager

- OPTVERIFYSIG could be a flag in STATE ?

- clean up $move and $hold since they basically do the same thing

- move more PGP specific code to pgp.c

- clean up ci_enter_string() to make the variable names have real meaning

- move the buffy notify code out of mutt_buffy_check() - eisenbud patch?

- remove use of short for message numbers to avoid the 65535 message limit

