Courtesy of Grace CoddingtonFor Grace Coddington, the best parties didn’t come with a proper guest list: Fashion shoots became dinners; then dinners drifted onto the dance floor. “When you went dancing, you were dancing. You didn’t go to be photographed dancing,” Coddington explains. “Perhaps the sign of a great party is that nobody thought to take a picture until it was over.” She was always more interested in what happened just before a party …