In post-spandex times, where the average superhero uniform comprises tactical gear the color of cement, James Gunn is one of the few directors who understands the allure of a good quirk. When the news of a greenlit Guardians of the Galaxy film hit the presses in 2012 and cynics accused Marvel Studios of scraping the bottom of the barrel, Gunn proved us wrong, turning in a swashbuckling space adventure that doubled as a heartrending found family story. Guardians of the…