add content negotiation feature, add context.ReadYAML and fix https://github.com/kataras/neffos/issues/1#issuecomment-515698536

Former-commit-id: 9753e3e45c7c24788b97814d3ecfb4b03f5ff414

_examples/websocket/basic/browser/index.html

@@ -53,6 +53,8 @@
         };
     }
 
+    const username = window.prompt("Your username?");
+
     async function runExample() {
         // You can omit the "default" and simply define only Events, the namespace will be an empty string"",
         // however if you decide to make any changes on this example make sure the changes are reflecting inside the ../server.go file as well.
@@ -70,6 +72,10 @@
                         addMessage(msg.Body);
                     }
                 }
+            },{
+                headers: {
+                    "X-Username": username,
+                }
             });
 
             // You can either wait to conenct or just conn.connect("connect")

_examples/websocket/basic/go-client/client.go

@@ -42,7 +42,10 @@ func main() {
 	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(dialAndConnectTimeout))
 	defer cancel()
 
-	client, err := websocket.Dial(ctx, websocket.DefaultGorillaDialer, endpoint, clientEvents)
+	// username := "my_username"
+	// dialer := websocket.GobwasDialer(websocket.GobwasDialerOptions{Header: websocket.GobwasHeader{"X-Username": []string{username}}})
+	dialer := websocket.DefaultGobwasDialer
+	client, err := websocket.Dial(ctx, dialer, endpoint, clientEvents)
 	if err != nil {
 		panic(err)
 	}

_examples/websocket/basic/server.go

@@ -68,8 +68,17 @@ func main() {
 		SigningMethod: jwt.SigningMethodHS256,
 	})
 
+	idGen := func(ctx iris.Context) string {
+		if username := ctx.GetHeader("X-Username"); username != "" {
+			return username
+		}
+
+		return websocket.DefaultIDGenerator(ctx)
+	}
+
 	// serves the endpoint of ws://localhost:8080/echo
-	websocketRoute := app.Get("/echo", websocket.Handler(websocketServer))
+	// with optional custom ID generator.
+	websocketRoute := app.Get("/echo", websocket.Handler(websocketServer, idGen))
 
 	if enableJWT {
 		// Register the jwt middleware (on handshake):