When you're Stephen Sondheim, you earn a standing ovation before you say a word " or play a note. So, naturally, that's what an enthusiastic crowd gave the Broadway legend when he stepped out on stage Monday night at New York City's Town Hall, where an audience of theater fans and stars watched the maestro sit behind a piano to play, and sing, "Good Thing Going," from his 1981 musical Merrily We Roll Along. That mesm…
