Jon Fosse’s "A Summer Day" is an enigmatic play, weighty, with repetitive dialogue and portentous glances. It is like a live Bergman film, a grim Scandinavian drama with mysterious overtones written to be purposely vague. Fortunately, Mr. Fosse, a Norwegian, has been translated and directed by Sarah Cameron Sunde and acted by six talented actors, led by Karen Allen making a remarkable return to the New York stage.