This commit implements the round-trip-time estimation algorithm from Tor
proposal 324, validating the implementation against the test vectors
found in C tor. (Note that at the time of writing, the new test vectors
may not be committed to C tor yet, but they will be soon.)
This also adds the necessary consensus parameters to `NetParameters`.
Some of them have been renamed in order to (hopefully) make them more
understandable.
Emil Engler
Nick Mathewson
eta