Bulb-channels

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* WebSocket generic views now accept connections by default in their connect
handler for better backwards compatibility.

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* BREAKING CHANGE: WebSockets must now be explicitly accepted or denied.
See https://channels.readthedocs.io/en/latest/releases/1.0.0.html for more.

* BREAKING CHANGE: Demultiplexers have been overhauled to directly dispatch
messages rather than using channels to new consumers. Consult the docs on
generic consumers for more: https://channels.readthedocs.io/en/latest/generics.html

* BREAKING CHANGE: Databinding now operates from implicit group membership,
where your code just has to say what groups would be used and Channels will
work out if it's a creation, modification or removal from a client's
perspective, including with permissions.

* Delay protocol server ships with Channels providing a specification on how
to delay jobs until later and a reference implementation.

* Serializers can now specify fields as `__all__` to auto-include all fields.

* Various other small fixes.

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* channel_session now also rehydrates the http session with an option

* request.META['PATH_INFO'] is now present

* runserver shows Daphne log messages

* runserver --nothreading only starts a single worker thread

* Databinding changed to call group_names dynamically and imply changed/created from that;
other small changes to databinding, and more changes likely.

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* New CHANNELS_WS_PROTOCOLS setting if you want Daphne to accept certain
subprotocols

* WebsocketBindingWithMembers allows serialization of non-fields on instances

* Class-based consumers have an .as_route() method that lets you skip using
route_class

* Bindings now work if loaded after app ready state

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* Bindings now require that `fields` is defined on the class body so all fields
are not sent by default. To restore old behaviour, set it to ['__all__']

* Bindings can now be declared after app.ready() has been called and still work.

* Binding payloads now include the model name as `appname.modelname`.

* A worker_ready signal now gets triggered when `runworker` starts consuming
messages. It does not fire from within `runserver`.

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* Data Binding framework is added, which allows easy tying of model changes
to WebSockets (and other protocols) and vice-versa.

* Standardised WebSocket/JSON multiplexing introduced

* WebSocket generic consumers now have a 'close' argument on send/group_send