Once a cause célèbre for its brutal subject matter, Phillip Ridley's electrifying Mercury Fur is celebrating its tenth year with considerably more acceptance at the New Group. One of the play's stars, Jack DiFalco, plays Darren, an innocent in a dystopia that is anything but. We sat down and talked with him about his role and the world of the play;Â he was even kind enough to lend us some insight into the notorio…