Fixed problem with SHOUT caused by frames being destroyed after sending to first peer

Please review. I added a test which demonstrates the problem (and had to change the existing ZrePing in the test as well).

For now, I just duplicated the message for sending to each peer in the group. There may be other solutions too. I also changed the codec to destroy frame fields in the destroy() method... Not technically necessary but I thought it would fix it at first, and now it seems logical to keep.
FYI: If you run this test without the other changes (to main source) applied, it should fail with an error.