qconfirm-check-mid(1) MUST have all lowercase MIDs!

i just found an issue with using qconfirm-check-mid(1) as an argument
to qconfirm-check(1) to automatically accept messages having local
message-IDs in the RFC-[2]822 References: or In-Replyto: headers.

q-c-mid(1) lowercases message lines, but not the message-IDs given as
arguments.  this will make it fail to recognize responses to locally
generated messages, so the remote end still has to confirm its own
reply!

gerrit, please make a note in q-c-mid(1)s documentation or let it
lowercase MIDs given either in .qconfirm/conf/QCONFIRM_MID or on the
command line.

this buglet was hard for me to track down, because i use several
message-IDs, one of which was given the way it was generated, with two
uppercase letters in it.  so i had replies where q-c-mid(1) worked and
many where it didn't.  the source is explicit about the cause, but i
actually didn't suspect that innocent piece where upper- to lowercase
conversion is done, since it isn't wrong in itself, it only leaves out
the same treatment for argument- or environment MIDs.

regards,

  clemens