handling multi-part email

Well, I've built up a list of headers not to display, and use it in the topics and default displays.

I've also managed to create an lsec for each mime-part.

The problem at this point is dealing with the displays of the message content. This is going to be a long road, starting with encoded text. I figure for html, I need to start using frames, too.

And then there's the attachments.