totally rework aliasing scheme -- sucks when no DBM now,

totally rework aliasing scheme -- sucks when no DBM now,
but works better for the usual case; fix some quoting problems
(and how many did I add?); remove .mailer feature since .forward
will simulate this happily

SCCS-vsn: usr.sbin/sendmail/src/alias.c 3.10
SCCS-vsn: usr.sbin/sendmail/src/deliver.c 3.18
SCCS-vsn: usr.sbin/sendmail/src/sendmail.h 3.23
SCCS-vsn: usr.sbin/sendmail/src/parseaddr.c 3.17
SCCS-vsn: usr.sbin/sendmail/src/util.c 3.7
SCCS-vsn: usr.sbin/sendmail/src/main.c 3.17
SCCS-vsn: usr.sbin/sendmail/src/readcf.c 3.8
SCCS-vsn: usr.sbin/sendmail/src/stab.c 3.5