* add "released" ack-response for "release" command, to sync w.close()
* move websocket URL to root
* relayurl= should now be a "ws://" URL
* many tests pass (except for test_twisted, which will be removed, and
test_scripts)
* still moving integration tests from test_twisted to
test_wormhole.Wormholes
This made sense for ServerSentEvent channels (which has no purpose once
the channel was gone), but not so much for websockets. And it prevented
testing duplicate-close.
Pass in a handle and a pair of functions, rather than an object with two
well-known methods. This should make it easier to subscribe to multiple
channels in the future.
but only if the client is modern enough to include "id" in the message,
which lets us avoid sending acks to an 0.7.5 client (which would cause
them to abort, they don't like unrecognized server messages).
The acks let the client learn the server_rx time of messages that
terminate on the server, like "allocate" and "claim".
