o Minor features (directory authority, relay):
    - Authorities now vote on a "StaleDesc" flag to indicate that a relay's
      descriptor is so old that the relay should upload again soon.  Relays
      understand this flag, and treat it as a signal to upload a new
      descriptor.  This flag will eventually let us remove the 'published'
      date from routerstatus entries, and save a great deal of space in our
      consensus diffs. Closes ticket 26770; implements proposal 293.