[Nmh-workers] Pager output on mhshow

[Ken Hornstein]

So I took at look at why our mhshow performs so lousy on pretty much anything.
The basic reasons are:

- mhshow defaults to "-pause"
- The default display for text content is %p$PAGER (%p asks for confirmation
  if -pause is set).

I looked at what meillo did; he got rid of pause support completely and
fed all output into a single pager process.  He also only supported text
content.  This strikes me as much better than what we do now.  But as
always, there are complications.

In MH/nmh, each part was processed individually.  Combining them all under
one pager works great for text parts, but if you have graphical content
then it sort of falls down, because you might want confirmation of that.
But in my experience, usually you can divide your content into two types:
text, and "everything else".  That suggests to me that a middle road might
be as follows:

- By default only display text, inline content (basically, default to
  -type text).  This means that configured display programs in the profile
  or mhn.default be designed to simply dump their stuff to stdout (I think
  current entries that output to a pager will work fine).

- Non-text entries will get a marker like:
  [part 2.2 image/jpeg A cool new picture!]

  in the output.

- If you specify a specific part or MIME type, you get that regardless of
  disposition setting.

Thoughts?  Better ideas?

--Ken