Change, especially the easygoing kind, takes time. But after a while, it starts to show. Such is the case at Swallow Hill, where in the few years since the venue moved to its present space and Jim Williams took over as director, the concert hall/music school has quietly turned into an entrenched community presence. Something goes on there almost every day, be it a coffeehouse jam session, gallery opening, song circle, recording session or major concert, and, as always, students of all ages come and go, lugging their guitar cases, mandolins, fiddles and autoharps hither and thither. Music lives in this old church building, and Swallow Hill's welcoming door always seems to be open.