tor/changes/16679_16685_etc

  o Major features (relay, Ed25519):
    - Significant improvements to the usability of relay-side Ed25519
      key management. Log messages are better, and the code can
      recover from far more failure conditions.  Thanks to "s7r" for
      reporting and diagnosing so many of these!

  o Major bugfixes (relay, Ed25519):
    - Avoid crashing on 'tor --keygen'. Fixes bug 16679; bugfix on
      0.2.7.2-alpha. Reported by "s7r".
    - Improve handling of expired signing keys along with offline
      master keys. Fixes bug 16685; bugfix on 0.2.7.2-alpha. Reported
      by "s7r".