April is International Guitar Month. If you didn’t know that, you’re not alone. When Sean McGowan, a guitar professor at the University of Colorado-Denver announced it at the King Center Friday night, even the star performer, John Scofield was surprised. He quipped that every month was guitar month for him, but he was glad to have three more weeks to celebrate officially. Scofield was in Denver as part of UCD’s Guitar Fest, a three-day celebration featuring several master classes and concerts, and his trio (with Steve Swallow on electric bass and Bill Stewart on drums) closed the festival with an 80-minute set that offered a wide range of musical styles, all molded to fit the parameters of a jazz guitar trio.