* 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
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