By Michael Cavna, The Washington Post One of the more common critical swipes at Marvel Studios’ Thor franchise has been that despite the comic chops of its stars, the tone has been as weighty as the superhero’s hammer, if not his gold-tress extensions. In “Thor: Ragnarok” (opening Nov. 3), the third film in the Asgard series, Disney/Marvel’s myth-laced muscleman sheds his long locks, and with them, it seems, the pseudo-Shakespearean gravity of the cinematic proceedings. Because fresh director Taika Waititi has lightened the mood, “Ragnarok” is the best-received Thor film so far among critics.