Adding function to pop3.el, and calling a backend from elsewhere

[Steinar Bang <sb@metis.no>]

I'll start out by explaining what I would like to do:
 1. Add a pop3-retrieve-headers to Rich Pieri's pop3.el back end,
    using the TOP command
 2. Interface reportmail.el (a biffish utility, as far as I can tell),
    to Gnus back ends (which would hopefully mean that I can later use
    it with IMAP, and maybe even with NNTP...).

So my questions are:
   i. is it possible?
  ii. is it stupid?
 iii. is pop3.el a regular back end?  Why, and how, use it, rather
      than POP with movemail (which is what I do today, appearently)
  iv. *can* pop3-retrieve-headers be added to pop3.el?  What about
      message numbers, and where should they be stored?  I assume the
      back end, and the POP daemon would have different message
      numbers...? 
   v. where could I find a good example of how to use a Gnus backend?
      The manual seems to have stuff on writing backends, and how to
      hook them into Gnus.  But I haven't been able to find anything
      on how to access a back end from emacs lisp

Not a priority matter.  Just something that has been cooking in the
back of my head, for a while.


- Steinar