Look, Up on the Auction Block! It’s the Original Artwork for Fleischer Studios’ Revolutionary 1940s ‘Superman’ Cartoons – dozens of never-before-seen production cels and model sketches soar in Heritage Auctions’ Dec. 11-13 Animation Art event. The first Superman cartoon hit the big screens on September 26, 1941. And nearly 80 years later, that 10-minute short,…