Released. Major new feature compared to Beta1:
- Messages are now always looped back (mcasts are discarded when copies
- DONT_LOOPBACK flag: mesages can now be dropped at the transport level
- Removed bottleneck when sending a message to a non-existent dest
- UNICAST3: connections to non-members are now closed more quickly
- SHARED_LOOPBACK_PING: new discovery protocol which always discovers
members in the same JVM. Used by unit tests.
- Hardened code for generating seqnos in UNICAST3 and NAKACK2