Sending mail

[David Pickens <dpickens iaesthetic com>]

For various reasons that aren't anyone's fault the multi-threaded code in
send.c wasn't really working well with with the changes taking place there
-- and while it worked fine for one e-mail at a time, large e-mails or
many small e-mails sent rapidly would fail or disappear.  Unfortunately,
for reasons that are convoluted, this became a problem for both
multi-threaded and non-multi-threaded versions.

In addition to this, it didn't seem to be 'reading' the sendmail error
codes well and the outbox loop which was re-enabled still doesn't work for
me.

I committed my first stab at fixing this, but it's an un-avoidably
complicated situation, so please try it and let me know if it works for
you.  (Because the outbox loop still wasn't working I disabled it -- we'll
fix this eventually, I'm sure. :)  ).

BTW - the new preferences dialogs are excellent!

David