tor/changes/bug17604

  o Minor bugfixes (connection usage):
   - Use NETINFO cells to try to determine if both relays involved in
     a connection will agree on the canonical status of that connection.
     Prefer the connections where this is the case for extend cells,
     and try to close connections where relays disagree on canonical
     status early. Also, additionally alter the connection selection
     logic to prefer the oldest valid connection for extend cells.
     These two changes should reduce the number of long-term connections
     that are kept open between relays. Fixes bug 17604.
   - Relays will now log hourly statistics on the total number of
     connections to other relays. If the number of connections per relay
     unexpectedly large, this log message is at notice level. Otherwise
     it is at info.