Today in history: On Feb. 11, 1990, South African anti-apartheid activist Nelson Mandela was freed after 27 years in prison. (Mandela would be elected president of South Africa four years later.) Also on this date: In 1847, American inventor Thomas Alva Edison was born in Milan, Ohio. In 1937, a six-week-old sit-down strike against General Motors ended, with the company agreeing to recognize and negotiate with the United Auto Workers union. In 1945, U.S. President Franklin D. Roosevelt, British