Barry Manilow's hits make his pop craftsmanship pretty obvious, but some might be surprised to learn that his skill is rooted in his days as a jingle writer, which he honors on the jubilant “A Very Strange Medley.” Jazz-tinged rave-ups like “Sweetwater Jones” and “dream duets” with the likes of Whitney Houston further flesh out his aspirations, and reveal how he came to be a premier song stylist.