Reserve websocket.extension name

[moteus]

Hello. I write extension plugin manager for websocket and permessage-deflate extension. I test it with my websocket implementation and it pass all AutoBahn tests (client and server).
I name it like websocket.extensions. In fact this module does not do any IO it just encode and decode already readed data and tell what need to add to handshake.
So I think it should be not difficult to add support extensions to your implementation.
You need just add ability to add headers to handshake to add Sec-Websocket-Extensions header.
And encode/decode RSV bits.

[lipp]

sounds good!