v0.3.0

• Feature: Add dedicated and faster RequestParser that also support the old
  inline request protocol.
• Feature: Message serialization can now be handled directly by the Serializer
  again without having to construct the appropriate model first.
• BC break: The Factory now has two distinct methods to create parsers:
  • createResponseParser() for a client-side library
  • createRequestParser() for a server-side library / testing framework
• BC break: Simplified parser API, now pushIncoming() returns an array of all
  parsed message models.
• BC break: The signature for getting a serialized message from a model was
  changed and now requires a Serializer passed:
  php ModelInterface::getMessageSerialized($serializer)
• Many, many performance improvements