Normally, when you find yourself paying attention to technical details in the theater, it means you’re bored and the production’s a flop. Not so with The Immigrant. Lighting designer Don Darnutzer’s effects were both lovely in themselves and integral to the musical’s theme: transparent skies with clouds flowing across them, the amber light of Sabbath candles. Ralph Funicello managed the same with his set, using pure, clean lines, muted colors, the shape of a lone house on endless plain and dry grasses rustling in clumps at the front of the stage.