Sigh. Well, this is it folks, the bottom of the barrel. Blumhouse, headed by Jason Blum, has been approaching pure, unadulterated terribleness for a good few years now (see: “The Exorcist: Believer,” “Halloween Ends” or any of the “Annabelle” films), but they’ve finally outdone themselves with “Night Swim,” director Bryce McGuire’s latest feature to hit...