Just in case you needed another reason to go cruising on your own boat, as opposed to signing up for a holiday cruise on an ocean liner, consider this: A violent brawl broke out between security guards and a group that had been terrorizing passengers for three days on the 963-foot-long Carnival Legend cruise ship from Melbourne, Australia.  The ship then made an emergency stop where 23 people, including many involved in the melee, were tossed off the liner. Some passengers described it as the “cruise from hell” as a group roamed the ship, strangling and punching passengers; others said…