Barely two months into his new job as the head of the world’s largest offshore driller, Steven Newman was steering Transocean through the 2010 Gulf of Mexico oil spill, quickly earning a reputation as a CEO with a steady hand. Newman also had to contend with two members of the 12-member board who represent activist investor Carl Icahn, who demanded a big dividend increase in 2013 and then saw it slashed by 80 percent this month in response to a sharp market downturn.