Also, we now disable confirmation to exercise a verifier mismatch. An
upcoming implementation change can probably detect the mismatch too
early otherwise, and throw WrongPasswordError before the test can
compare the verifiers.
This allows the Wormhole setup path to be simpler: consistently doing a
claim() just before watch(), regardless of whether we allocated the
channelid (with get_code), or dictated it (with set_code or
from_serialized).
The websocket lives on a Resource of the main rendezvous web site, and
the websocket URL is derived from the main "relay_url", so there's no
extra port to allocate, and no extra service to shut down.
