Jenny Scheinman is a catalyst of beautiful moments. Once, while recording an album with Lucinda Williams she coaxed the whole crew up to the roof for a candlelight dinner. Magical. Another time, she brought Paul Motian and Jason Moran together for a trio concert at the Village Vanguard. Superb. And one night, she invited banjo master Danny Barnes to join her at Barbes. The result: a space jammed with banjo players. Terrific. Last month the......