Editor’s note: Sign up for Unlocking the World, CNN Travel’s weekly newsletter . Get news about destinations, plus the latest in aviation, food and drink, and where to stay. CNN  —  In travel news this week: crackdowns on overtourism in Florence and Pompeii, new developments in the world of long-haul and ultralong-haul flights, plus the California couple who moved to France, where things did not go as they hoped. Launch of the Airbus A321XLR It’s slim, it’s sleek, it has a third fuel tank, and