I always wondered about a cruise line that sells rooms for almost less than it costs to feed a person in a week. But now is not the time to dump on Carnival Cruises.  The company is doing its best to right itself in troubled waters. Its most notorious mishap — when the Carnival Triumph lost power and stranded passengers in squalid conditions for five days — was followed last week by the Carnival Dream stuck in St. Maarten with engine trouble and the Carnival Elation hampered by steering problems. These mishaps prompted the company to review its fleet. One result: It is canceling 10 sailings on the Carnival Triumph and two European sailings on the Carnival Sunshine. Such hopeful, perky names. I only hope that any future ship will be called Carnival Miracle. That may be just what the cruise line needs.