Fears of casino boats potentially colliding with real working vessels on busy waterways was a core tenant of the drive to keep the vessels permanently moored at dock. Those fears became reality on Monday, but thankfully without disastrous results. A casino boat en route to its Indiana port and a barge carrying cement collided on the Mississippi River, causing extensive damage to the gambling boat, the Coast Guard said, but only slightly injuring one onboard the gambling boat. The northbound "Miss Belterra," owned by Pinnacle Entertainment Inc., limped to the shoreline near Caruthersville, Mo., where it was grounded safely. The 313-foot (95-…