Debianization

This makes the latest qpsmtpd buildable as a Debian package. I accomplished this by running dh_make fresh, then piecemeal incorporating bits from Devin Carraway's Debian package, version 0.84-11 (https://packages.qa.debian.org/q/qpsmtpd.html), and cleaning up Lintian warnings.

It would still be good to do some man page cleanups to make Lintian happy, but I feel that can be done as a separate PR at a later time.