[Mimedefang] feature request: ESMTP args

[John Nemeth]

     Would it be possible to add the capability to have ESMTP args
passed to filter_sender() and filter_recipient(), i.e.

MAIL FROM:<addr> SIZE=N ...
RCPT TO:<addr> ORCPT=<addr> ...

I checked the Milter API and apparently sendmail passes these in argv
when it calls xxfi_envfrom and xxfi_envrcpt, however there is no
mention of them in the mimedefang_filter manpage.