Make received OOCSIEvents remember their receiving client

Example Processing code:

    import nl.tue.id.oocsi.*;
    import nl.tue.id.oocsi.client.*;
    import nl.tue.id.oocsi.client.protocol.*;

    void setup() {
      OOCSI recipient = new OOCSI(this, "myrecipient", "localhost");
      recipient.subscribe("mychannel");

      OOCSIClient sender = new OOCSIClient("mysender");
      sender.connect("localhost", 4444);

      new OOCSIMessage(sender, "mychannel").data("mykey", "myvalue").send();
    }

    void handleOOCSIEvent(OOCSIEvent event) {
      println(
        event.getRecipient(),  // returned mychannel, now returns myrecipient
        event.getChannel()     // returned mychannel, still does so
      );
    }