[Nmh-workers] merge spost into post

[David Levine]

I'm thinking about merging the spost sendmail interaction
method into post.  spost doesn't speak SMTP, but rather
feeds the entire message to sendmail -t.  That would be easy
to add to post without making a mess.

We'd need a new mts value, in addition to the current "smtp"
and "sendmail", in mts.conf to select it.  "spost", unless
there's a better idea?  -t doesn't have much of a description.
sendmail calls it "GrabTo" internally, which is a bit more
descriptive but just doesn't appeal to me.

We could then remove spost and let its users pick up all of
the wonderful post features.  If there's a need to provide a
replacement for spost that would forward to post, that
wouldn't be difficult.  It would be triival if we added a
command line option to post to select the mts method, but I
don't know if that's worth doing unless it would be useful
by itself to override the mts setting from the command line.

spost has these command line options that post doesn't:

  -noalias    to disable nmh alias expansion
  -[no]push   to (not) fork/exit before exec'ing sendmail
  -[no]backup to (not) copy the sendmail input to a .bak file
  -[no]remove to (not) remove the sendmail input file

I don't see a need to support any of these in post, let
me know if you disagree.

David