Former U.S. Sen. Arlen Specter, longtime Senate moderate and architect of one-bullet theory in JFK death, died Sunday at age 82. (Associated Press file | Susan Walsh) ][/caption]PETER JACKSONAssociated PressHARRISBURG, Pa. ??? For most of his 30 years as Pennsylvania???s longest-serving U.S. senator and prominent moderate in Congress, Arlen Specter was a Republican, though often at odds with the