clean up error return messages

fix bogus "infinite loop" diagnostic; log better diagnostic info

fix excessive matching problem

fix a few problems pointed out by Neil Rickert; $~ matches only
one token

implement multi-word classes

recognize -a flag in dequote map

add dequote pseudo-map

improved debugging; pass convtime a default units; allow addition
of Comments: and stripping of Return-Path:

delete e_sender and e_returnpath; fix some bugs in envelope splitting

don't send all addresses through recipient rewriting in buildaddr;

change (simplify) user and host UPPER => lower case mapping

undo patch allowing prescan to return null vector; it breaks far
too much

allow host on local addresses; don't do domain extension on
return path, ever -- for <> addresses

consider addresses "different" if their uids differ

allow prescan to return a null vector; fix some duplicate prescan errs

changes for ESMTP; mostly better delimiter character pointer passing

allow $@ on LHS to indicate match zero tokens

overhaul status of SMTP reply codes

M_LOCAL => M_LOCALMAILER to avoid conflict with Ultrix <sys/mount.h>

close cached MCI connections after a fork; add p (privacy) and b
(min blocks free) options; fix selfref code; clean up $#error format

fix a variety of bugs found by Eric Wassenaar <e07@nikhef.nl>

move the meta-characters from C0 into C1 space

add "c" mailer flag to suppress all comment info in addresses

clean up log levels; allow IDA-style split header/envelope rewriting;
extend arpatounix with more zones (but is this even needed?)

Allow saving in ~/dead.letter; clean up VRFY output; fix bogus
error message in udbexpand; null terminate host buffers in buildaddr
(broken in 6.21).