websocket: Initial <websocket> client actor support.

websocket: Initial <websocket> client actor support.

* 8sync/systems/websocket/client.scm (no-op): New procedure.
(<websocket>): Change from record to actor and use it.
(websocket-init): New method.
(set-nonblocking!): New procedure.
(make-client-socket): Use it.
(make-websocket): Rename to...
(websocket-open): ...this new method and change accordingly.
(close-websocket): Rename to ...
(websocket-close): ...this new method and change accordingly.
(handshake, websocket-send, websocket-connecting, websocket-open?,
websocket-closing?, websocket-closed?): Change to method and update
accordingly.
(display-websocket): Move to...
(write)[<websocket]: ...this new specialization.
(set-record-type-printer!): Remove.
(websocket-loop): Renamed from...
* 8sync/systems/websocket/server.scm (websocket-client-loop): ...here.
(make-websocket-actor): New procedure.
(<websocket-server>): Call it for websocket upgrade, create new
<websocket> actor.
* demos/websocket/8s-client.scm,
demos/websocket/8s-server.scm,
demos/websocket/ws-client.js,
demos/websocket/ws-server.js: New files.
* Makefile.am (EXTRA_DIST): Add them.