perconnbwrate/burst not reset when config options change
If I have perconnbwrate/burst set to something, and an OR conn arrives, the rate and burst for that conn are chosen forevermore at that moment. If I later change the config options and hup, new OR conns get the new options, but old ones stay as they are.
This is going to become even more apparent once we put the options in the consensus. Our experiments won't produce the results we want because they'll be spoiled by already-established OR conns.
So we should walk through all the OR conns whenever those options change (including if they change in the consensus), and reset rate and burst to the new rate and burst, and if the bucket is now higher than burst, set it back to burst too.