PLOTS Conventional Wisdom Grassy Knoll No hay there. JFK buffs have moved on to Mumbling Woman and the Three Tramps. Oct. Surprise Sources very dubious. But CW still likes the smell of treason in the morning. M. L. King Plot Jesse Jackson, in foreword to J. E. Ray’s new book, calls for spec. prosecutor. Why not? Pearl Harbor Did FDR know? CW’s so weary of the 50th anniversary, it doesn’t care anymore. R. Maxwell Old CW: Capt. Bob killed for fortune. New CW: Capt. Crook walked his own plank. Moon Landing Staged in a studio? Millions thought ‘69. Oliver Stone, call your office.