By Linda Sieg, Yuko Yoshikawa and Tetsushi Kajimoto TOKYO (Reuters) - When ill health and political gridlock forced Shinzo Abe to quit after one dismal year as Japan's prime minister, his pride was dented and his self-confidence battered. One thing, however, was intact: his commitment to a controversial conservative agenda centered on rewriting Japan's constitution. Conservatives see the 1947 pacifist charter, never once altered, as embodying a liberal social order imposed by the U.S. Occupation after Japan's defeat in World War Two. ...