Jean Shepherd died last fall and, I realize now, not enough attention was paid. Shepherd was a genius of radio, a precursor of Garrison Keillor and better than Keillor (who IS very good). He was, above all, a storyteller and he would sit in his studio at WOR in New York night after night, enchanting his listener with tales. Shepherd is perhaps best remembered as the author of "A Christmas Story," an amusing, nostalgic story that, in its movie form, has become a holiday perennial, but his great talent was his ability to talk all night long in a manner that engaged the inquiring mind. . .