The metaphoric symbolism of traditional musicians performing inside a museum wasn’t lost on button accordionist Máirtín O’Connor, fiddler Cathal Hayden and bouzouki player Garry O’Briain. “Someone will put a friggin’ glass case over us – fossils of folk,” quips O’Connor, the former De Danana and Boys of the Lough alumnus, to much laughter. “We’ll sit here for the rest of our days.” In such an unlikely event, the Ulster Museum would be exhibiting the wrong musicians, for despite deep roots in Irish folk music, O’Connor, Hayden and O’Briain have, over the course of forty plus years, embraced all manner of…