October 16, 2012 By Stephanie Adrian   British baritone Simon Keenlyside and pianist Pedja Muzijevic presented an exceptional, if not mind-blowing, recital Saturday night at Clayton State University’s Spivey Hall. It was the sheer breadth of the sung poetry, as well as Keenlyside’s tremendous range of vocal color and nuance, that left one overwhelmed. Keenlyside won the Solo Vocal Award at the 2012 Gramophone Awards for his recording “Songs of War.”The first half of Saturday’s performance included roughly half of the 29 English songs on that album. Not all of them are overt statements about war, but they are presented…