With its autobiographic feel and its “memory play” structure, “The Marriage of Bette and Boo” feels like Christopher Durang’s most personal play, but who knows? Our darkest comic absurdist writes his “Long Day’s Journey into Night”, his “Glass Menagerie,” and the effect, let us say, is rather funnier than those two. Devastatingly, squirmingly funny and sad. His angriest and most mature work.