config: add a read limit option to the connection.

By default, the read limit is never set by NewConnection.
When using the default pool dialer, a read limit of 512KB is set.
When the read limit option is set, all sockets passed to NewConnection have that read limit set.

types/types.go

@@ -23,6 +23,7 @@ type Socket interface {
 	SetWriteDeadline(t time.Time) error
 	SetCloseHandler(h func(code int, text string) error)
 	SetPongHandler(h func(appData string) error)
+	SetReadLimit(limit int64)
 }
 
 type ReceivedMessage struct {