When Warren Zevon emerged in the midst of L.A.’s vibrant singer/songwriter scene in the mid-’70s, he was like a breath of…well, strange air. As a songwriter, Zevon bore little resemblance to the other leading craftsmen of the day, such as his friends Jackson Browne (who produced Zevon’s brilliant first Asylum album), Don Henley and Glenn Frey of The Eagles, or J.D. Souther. Zevon’s vision was darker, more bent than that of his peers. Critics invariably talked about his debt to…