* construct our own Qpsmtpd::Transaction object for testing, so we're sure
to have a pristine state
* Move some logic into a should_scan() sub, to help separate scan_all from
is_not_multipart (since the multipart state of a message has nothing to
do with any configuration parameters)
* includes full test converage for Qpsmtpd::Config
* folded t/config.t into t/qpsmtpd-config.t
* includes additional tests for Qpsmtpd
* folded t/tempstuff into t/qpsmtpd.t
* PBP adjustments here and there
* other tweaks to handle test warnings
