Initial design of UNICAST3 SYNC
- New simplified design without states and SYNC-ACK
- Implemented Bits.size(int), Bits.readInt() and Bits.writeInt()
- Reverted changed to UNICAST3
- Updated design of UNICAST-SYNC.txt
- Added timestamps to ACK and SEND-FIRST-SEQNO msgs (https://issues.jboss.org/browse/JGRP-1875)