GoldmineBy Bruce SylvesterExcerpted: The Wailin’ Jennys opened the three-stage event with meticulously arranged three-part harmonies. Their “Bring Me Little Water, Sylvie” came from Leadbelly, “Light of a Clear Blue Morning” from Dolly Parton. There was little concern for purism here (unlike at the ’65 festival, where Bob Dylan controversially went electric and Seeger tried to chop his power line with an axe). Conservatory-trained Heather Masse — a Maine native among the trio’s two Canadians — lent jazz touches, while backup violinist Richard Moody (brother of the Jenny’s Ruth Moody) provided classical grooves to the pristine Jenny sound. (And no, the Jennys haven’t heard from the family of Waylon Jennings.)