Alcoa (AA) kicked off the unofficial start of earnings season by reporting fourth-quarter revenue above views after the market closed. The aluminum manufacturer said Q4 EPS was a 6-cent gain vs. a 4-cent loss in 2011, in line with analyst estimates. Revenue fell 2% to $5.9 billion as the average price per ton of aluminum fell slightly. But that beat analyst expectations of $5.6 billion. The company, viewed by many as an economic bellwether because