[Nmh-workers] Re-worked test suite

[Ken Hornstein]

Greetings all,

With the encouragement of David Levine, I am pleased to announce that I've
reworked the test suite so it now functions nicely with Automake.  To use
it you can run "make check".  It also gets run automatically as part of
"make distcheck".  I think I've got it right, but please let me know if
it doesn't work.

It should be noted that the nmh test suite was originally written by
Josh Bressers and recently been updated by David Levine.  Thanks to both
of them for all the work that they've done here!

Oh ... good thing I looked at the logs.  There are also significant
contributions by Peter Maydell and Eric Gillespie.  Thanks guys!

--Ken