Pop artist Peter Max, whose vibrant 1960s art led to massive commercial success, has died at age 88. (Barry Brecheisen / Invision / Associated Press)Peter Max, the pop artist and hippie icon who helped define the vibrant psychedelic style of the 1960s and whose work graced posters, album covers, T-shirts, dinnerware, postage stamps and beyond, has died. He was 88.Max died Monday at a Manhattan hospital, according to a statement provided to the New York Times by his son, Adam Max. No cause of death was provided, but Peter Max had been suffering from advanced dementia, according to the Associated...