Comic fans with a touch more gray at their temples than they’re probably comfortable with will recall that in 2008, just as Iron Man fever reshaped blockbuster movies for a generation, Marvel Comics published a Marvel Knights spinoff miniseries, Iron Man: Viva Las Vegas, written by the film’s director, Jon Favreau. It was planned for a four-issue run, with Iron Man and Fin Fang Foom wreaking havoc on Sin City, yet only two issues were published …