Exactly a year ago we reported as follows on Mary Poppins: ""It's a natural. The grown-ups will take it from the children; the children will take it from the grown-ups. And everyone will have a good time getting acquainted with Mary Poppins, the upside-down sort of nurse....Humor that is fun --exaggeration, absurdity, imagination plus....Watch it."" --Now comes its sequel, and, frankly, we were a bit nervous about it. We had been so encouragingly right last year. Would Miss Travers uphold us this year? --A sigh of relief. She's done it again. Mary Poppins is not just a flash in the pan. She's here to stay. The same refreshing spontaneity, the same originality. She doesn't even imitate herself -- any more than one demands in seeking a sense of familiarity. And Mary Shepard has outdone herself in the illustrations. Dates -- November 14 for the east; November 21 for the west.