Cro::WebSocket::MessageSerializer

A Cro::Transform that consumes Cro::WebSocket::Message and produces Cro::WebSocket::Frame. It handles Message bufferization, e.g. all emitted Frames will be sent in a correct order. However, if control message is received(i.e. one with opcode equal to Close, Ping or Pong), it will be emitted as soon as possible.