WIP - not yet hooked in

This is a portion of release 1.0.0 of MiniDNS from https://github.com/MiniDNS/minidns/ 2020-07-18
Only contains the minidns-core portion of the library.
Removed tests, most util classes, and DnsRootServer class.
Unmodified, as a base for future checkins.
Total size of zipped classes is about 75 KB.

This software may be used under the terms of (at your choice)
- LGPL version 2 (or later)
- Apache Software licence
- WTFPL