a message is posted to a different conference than the original sub-board with
completely different header information. I suspect this has something to do
HEADERS.DAT creation or import - not sure. So I added a "Conference"
headers.dat field for *messages* (it already existed for votes) and use that
value to confirm that the message header at the associated offset value in the
QWK packet has the same conference number as the section in the headers.dat
file. This is really just a sanity check and will only catch messages that were
mistakening cross-posted (to a different conference) - *but* it log errors and
save the bad QWK or REP file for me to examine more closely and see what's
going on - and the message won't be imported (just "lost", which is also bad).

So added more QWK import success/error checking and logging (especially for QWK
packets since REP importing already had a lot of stats covered).

Another check would be to store the original message number in the headers.dat
file as well and use that to confirm that the headers.dat section is the
correct match for the QWK message at that offset. I did not implement this
check, yet. The conference number check seems like it'll catch most of the bad
msgs and lead me to the root-cause.