Lynn's apartment over Silberman's Books. August 3rd, 2014. 7:54pm   A letter had arrived at the Espadas School of Self-Defense and Swordsmanship from Lynn Epstein, with a familiar West End address. Inside, was a handwritten note; the penmanship was graceful, almost archaic, but the writer's voice was unmistakable.    The changeling was pacing again; it was humanly impossible to prepare for an evening like this, but Lynn had given it the good old never-finished-college try. The furniture was w