People soon will be able to carry guns and other dangerous weapons onto the grounds and parking lots of Reagan National and Dulles International airports, after officials yesterday eased what they said were overly restrictive rules. Without debate, the board of the Metropolitan Washington Airports Authority unanimously agreed to permit passengers and other airport visitors to carry guns, knives and other weapons as long as they keep them out of terminals and other buildings that access airfields. Passengers who are taking guns with them on flights still will be allowed to carry them into the terminal but are supposed to...