The cacophony of angry voices is a hammer to the head in Tony Kushner’s play at Denver’s Curious Theatre. Then there’s the literal hammering. And the annoying clapping. Sometimes all at once. Angry shouting, hammering, clapping. The result is a three-act, 3 1/2 hour endurance test, a bombardment of words and ideas built to be challenging. “The Intelligent Homosexual’s Guide to Capitalism and Socialism with a Key to the Scriptures,” Kushner’s 2009 play first conceived as a novel, has for years undergone rewrites.