Receive server pong by client ping

[yura999999999]

Hello! First of all, tnx for Merged #95

I want to share my idea of improving the library.

The best way to check socket status(check server alive) - send clients ping:

$loop->addPeriodicTimer(mc::socketCheckInterval, function() use($client, $logger){
    $frame = WebSocketFrame::create(WebSocketOpcode::PingFrame);
    $client->sendFrame($frame);
    $logger->notice("ping");

    //DO SOMETHING
});

And receive server pong:

$client->on("pong", function($frame) use ($logger, $client){
    $logger->notice('pong');

    //DO SOMETHING
});

Also, it is very important sometimes to look at the server's response:

$client->on("pong", function($frame) use ($logger, $client){
    $logger->notice('pong');

   var_dump($frame->getData());
   var_dump($frame);
});

Maybe my suggestion needs to be improved or changed, but in the simplest form, PONG is needed