Correct and update Prop324 based on things learned in prototyping

While testing congestion control over onion services, I noticed some omissions from the proposal that were present in the background material and literature, as well as some new heuristics I discovered from testing the prototype:

1. The congestion window only should be updated with a congestion signal once per window
2. If the local orconn is blocked, that should be an immediate congestion signal. Also doc that we may have too large a queue there
3. If the edge connections do not have data to send, estimates of BDP should not be updated
4. Westwood may have a runaway condition where max RTT continues to grow. We may want to reduce the max RTT measurement upon congestion
5. I made a congestion control algorithm that directly uses the current BDP estimate as its current congestion window, and this works. We should spec it and evaluate it in Shadow.
6. Update the consensus parameter list and tuning experiments section
7. BDP estimation algs