This episode's headline: TV Violence. The guests include Dr. THOMAS RADECKI, National Coalition on TV Violence; Dr. DAVID PEARL, National Institute of Mental Health; Dr. ALAN WURTZEL, American Broadcasting Company; ERIC MINK, St. Louis Post-Dispatch. Byline: In Washington: JIM LEHRER, Associate Editor; In New York: CHARLAYNE HUNTER-GAULT, Correspondent; JOE QUINLAN, Producer; MAURA LERNER, MARIE MacLEAN; Reporters