Ronen Zvulun/ReutersJacob Rothschild, the British financier and philanthropist who built his own empire after walking away from his family’s, has died. He was 87.His death was confirmed on Monday by his family, who told the Associated Press in a statement that Rothschild, formally known as the fourth Baron Rothschild, had been “a towering presence in many people’s lives, a superbly accomplished financier, a champion of the arts and culture, a devoted public servant, a passionate supporter of cha