The first snow just fell and we’re already looking forward to Commonwealth Shakespeare’s next free Shakespeare on the Common. Can you blame us? The theater company announced Monday it will do “Twelfth Night,” the Bard’s comedy of love in disguise, for its 19th season next summer. “We wanted to bring back an audience favorite — and one of my favorite comedies,” CSC artistic director Steven Maler said in a statement. “We are eager to revisit Illyria and some of Shakespeare’s most colorful characters — Sir Toby Belch, Malvolio, Sir Andrew Aguecheek, and Feste.” Show dates have not been announced.