Heroine Diana Bishop is a Yale professor spending a year at Oxford. Her amazing intellect is aided by "a prodigious, photographic memory" — and that's not all she has going for her: She's described as an "extraordinary" actress and a disciplined athlete who is constantly rowing or jogging. You sort of want to kick her. But A Discovery of Witches turns out to be a fine story that's increasingly charming, centered on Bishop's discovery of a manuscript that promises to unleash all