• First stable release, now following SemVer

• BC break: Consistent public API, mark internal APIs as such (#38 by @clue)

  // old
  $client->on('data', function (MessageInterface $message, Client $client) {
      // process an incoming message (raw message object)
  });
  
  // new
  $client->on('data', function (MessageInterface $message) use ($client) {
      // process an incoming message (raw message object)
  });
  

Contains no other changes, so it's actually fully compatible with the v0.5.2 release.