Saxophonist Steve Coleman swore that he was so far under the underground that few outside his community of fellow performers appreciated his idiosyncratic approach to music. For the Allentown horn player who could be inspired by circulatory systems and bird calls, no sound is off-limits. But evidently, someone has been listening. Last month, Coleman was roused out of bed by a phone call from the MacArthur Foundation. He had won what is known as a “genius grant,” a $650,000 prize awarded over five years.