plug rfc2822 parser to smtp_session but do not process lines yet
feed rfc2822 parser but do not register callbacks yet
iobuf_queue() does not return len ...
all header and data lines now pass through the rfc2822 feeder
masquerade _smtp-in_ code path to fix an interop issue with other MTA
when dealing with older MUA that do not append their domain
Merge branch 'master' into portable
add rfc2822 and rfc822 parsers to the build