Parse contacts, chats, and new incoming messages (!); keep connected with pings

- We now actually parse the contact and chat information we get sent after
  the connection handshake.
- A massive protobuf autogenerated file has been added, which takes care of
  parsing the actual WhatsApp message objects -- i.e. the actual chat messages.
  We still need to actually translate that protobuf into something more
  usable though.
- Also, we don't disconnect now, because we actually send pings.