A man whose job as the Weather Underground’s “bomb guru” is revealed in an explosive new book taught at New York City public schools for nearly 25 years and now receives a $40,000 annual pension.Ronald Fliegelman is one of the unsung members of the Weather Underground, co-founded by former Obama associate Bill Ayers in 1969.The son of a Philadelphia doctor, Fliegelman became the radical leftist group’s chief bomb architect after three members — Terry Robbins, Diana Oughton, and Ted Gold — were killed on March 6, 1970 when a bomb they were making detonated at their Greenwich Village apartment....