Guardians of the Galaxy, Marvel’s big summer movie, is a hot-blooded, swaggering space-opera blockbuster and a finely-judged exercise in controlled chaos. On the one hand, it’s another big-budget, aggressively promoted film from the production factory of Marvel Studios, which has achieved unprecedented box-office success through shrewd creative decisions and a tight-fisted promotion of a ‘house style’ across their properties. On the other hand, they chose as writer-director (with co-writer Nicole Perlman) James Gunn, whose CV includes Super, in which a psychotic Rainn Wilson dresses as a superhero and runs around smashing people’s faces in with a wrench, and Tromeo and…