new plugin "lmtp" - turn qpsmtpd into LMTP server
new plugin "lmtp" - turn qpsmtpd into LMTP server

The lmtp plugin turns qpsmtpd into an LMTP server, see RFC 2033. This
includes:
 * removing the "HELO" and "EHLO" keywords and adding the "LHLO" keyword
 * change the greeting line to match "LMTP" instead of "ESMTP"
 * returning the queue status for each recipient separately
The RFC requirement of supporting ENHANCEDSTATUSCODES (RFC 2034) is not
implemented: the core lacks support for it.

Currently no support for STARTTLS (plugins/tls) and AUTH (plugins/auth/*).

vetinari/qpsmtpd,vetinari/qpsmtpd