ssdp-responder v1.9

The Dennis Ritchie release.

Changes

• Add command line options to ssdp-scan, mostly for testing but may
  be useful for other purposes too
• Use $ac_default_prefix instead of /usr/local in configure script
  when expanding paths
• Update copyright years (affects LICENSE file hash)
• Add ChangeLog to project
• Drop Travis-CI in favor of GitHub Actions

Fixes

• Fix #6: workaround for OpenVPN /32 default server setup
• Fix #9: time-of-check vs time-of-use issue with caching of UUID,
  found by Coverity Scan, fixed by Raul Porancea
• Fix #10: basic instructions for building and starting the daemon