sliding window

[lxzan]

I see that the master branch has a new NewWriterWindow function, can I use it to implement the full WebSocket RFC7692 compression extension?

Thanks for your great work

[klauspost]

@lxzan It does indeed seem so.

[lxzan]

I'm going to have to add a bunch of ugly if else to support the client_max_window_bits/server_max_window_bits parameters of the websocket permessage-deflate extension :(