Slightly more robust, implement fragmentation

* hunchensocket.lisp (websocket-client): typo.
(send-message): New function, exported.
(read-frame): Re-format error message.
(read-frame): Return FINP in return list.
(handle-frame): Implement state machine according to RFC.
(websocket-loop): Simplify READ-HANDLE-LOOP.
(websocket-handle-handshake): Make a method and export. Maybe
application wants to set specific headers.
(websocket-handle-handshake): :SEC-WEBSOCKET-PROTOCOL header-out
selects first of header-in.
(Chat example): Removed from this file.
Update README.md
Fix "Connection: Closed" bug

* hunchensocket.lisp
(websocket-handle-handshake, acceptor-dispatch-request): Fix bug
where browsers couldn't connect because Hunchentoot declares
connection closed.