* Create different strategies for exploratory tunnels (which are difficult
      to create) and client tunnels (which are much easier)
    * Gradually increase number of parallel build attempts as tunnel expiry
      nears.
    * Temporarily shorten attempted build tunnel length if builds using
      configured tunnel length are unsuccessful
    * React more aggressively to tunnel failure than routine tunnel
      replacement
    * Make tunnel creation times randomized - there is existing code to
      randomize the tunnels but it isn't effective due to the tunnel creation
      strategy. Currently, most tunnels get built all at once, at about 2 1/2
      to 3 minutes before expiration. The patch fixes this by fixing the
      randomization, and by changing the overlap time (with old tunnels) to a
      range of 2 to 4 minutes.
    * Reduce number of excess tunnels. Lots of excess tunnels get created due
      to overlapping calls. Just about anything generated a call which could
      build many tunnels all at once, even if tunnel building was already in
      process.
    * Miscellaneous router console enhancements