[tor-relays] max / burst speed

[grarpamp]

> I run 2 middle nodes, one at 150KB/300KB and the other at 100KB/200KB.

Then there is the question of just what is the correct range of burst values
to use. In a former life, working with real network hardware, the burst
setting was definitely NOT 2x the average rate. It was more like
1.08x. It had to do with the shaping method in use and the time
period it averaged over. I can't seem to find the links at Cisco. Setting
it too high did nothing as the averager clamped in anyways. Too low
guaranteed other traffic but needlessly choked the shaped traffic.
Just right kept things bursty enough to stream nicely as needed.

No idea what shaping algorithm Tor uses, nor any clue on recommended
burst ratios under said algorithm. Anyone???.