Photos by Jay Lee"Now and then it keeps you runnin', never seems to die..." The opening line to Son Volt's soothing elegy "Windfall," which closed out Tuesday's main set at the Continental Club - just like almost every other SV set since the band's 1995 debut Trace - goes a long way to explain why Jay Farrar is still hanging around all these years since Son Volt and Wilco sprang from his and Jeff Tweedy's uncomfortable Uncle Tupelo divorce. "It" is that mysterious impulse to keep writing s