Just what you didn't want to see happen in Cuba: the coming of cruises disgorging thousands onto the shores of the island nation. But hold the phone. The announcement Tuesday that Carnival Corp. will begin sailing to Cuba in May may have raised the "that-will-spoil-everything" alarm, but Carnival is deploying its new Fathom brand, using a relatively small (710-passenger) ship that parts ways with the concept of cruises that party hearty ... Fathom cruises are designed to provide "cultural, artistic, faith-based and humanitarian exchanges between American and Cuban citizens," Carnival said. Americans are allowed to travel to Cuba under these...