(© Glyndebourne Productions Ltd. Photography by Richard Hubert Smith) By the time the current run of “Le nozze di Figaro” is concluded, Glyndebourne will have hosted its 600th performance of Mozart and Da Ponte’s perennial masterpiece. The opera launched the  country house enterprise in 1934 at the behest of Fritz Busch and Rudolf Bing, who wisely cautioned against Christie’s Wagner-shaped {…}