Dynamite's series of comic books and graphic novels based on Grumpy Cat, the online sensation-turned-cultural icon, have sold over 500,000 copies! The incredible success of Grumpy Cat in comics, which included the sale of over 100,000 copies of Grumpy Cat Vol. 1: Misadventures in multiple printings, now includes an additional 140,000-unit print run of the world's favorite fractious feline in an…