permessage-deflate is a compile-time feature (API Change):

fix #849

This adds an additional `bool` template parameter to
`websocket::stream`:

* When deflateSupported is `true`, the stream will be capable
  of negotiating the permessage-deflate websocket extension per
  the configured run-time settings.

* When deflateSupported is `false`, the stream will never negotiate
  the permessage-deflate websocket extension. Furthermore, all of the
  code necessary for implementing the permessage-deflate extension
  will be excluded from function instantiations. The resulting emitted
  object code should be smaller.

test/doc/websocket_snippets.cpp

@@ -57,7 +57,7 @@ boost::asio::ip::tcp::socket sock{ioc};
 
 {
 //[ws_snippet_6
-    std::string const host = "mywebapp.com";
+    std::string const host = "example.com";
     boost::asio::ip::tcp::resolver r{ioc};
     stream<boost::asio::ip::tcp::socket> ws{ioc};
     auto const results = r.resolve(host, "ws");
@@ -310,6 +310,16 @@ struct custom_wrapper
 
 //]
 
+//[ws_snippet_26
+
+// A WebSocket stream
+template<
+    class NextLayer,
+    bool deflateSupported = true>
+class stream;
+
+//]
+
 } // doc_ws_snippets
 
 //------------------------------------------------------------------------------