Where would Jonathan Levine be today if the Weinsteins had actually released All the Boys Love Mandy Lane in 2007? Few indie, D.I.Y. slashers have a history that’s quite so storied as this one’s; Levine started work on the project in 2003, completed it and sold it to Bob and Harvey in 2006, and then went on to make a name for himself with The Wackness in 2008 while Mandy Lane languished in obscurity. (And that’s just the short version of events.) If you’re wondering why a play on “kids go to isolated wilderness, kids get dead” exploitation wound up sitting on a shelf for nearly seven years, chalk it…