Miss Jane Marple, heroine of many Agatha Christie novels, has been presented in many ways: the formidable dowager of Margaret Rutherford; the fragile but quick-witted gentlewoman of Joan Hickson; even the sprightly, clever but seemingly innocuous retired woman of Helen Hayes. To that list we can now add the open-minded, not quite laid back student of human nature that is presented by Geraldine McEwen in a new season of Miss Marple Mysteries on PBS