When it comes to romantic matchups, Hollywood has never been particularly shy about pairing a conventional human being with a fluky, not-of-this-earth partner: a mermaid, a superhero, King Kong, or Zach Galifianakis. But “Every Day,” an adaptation of David Levithan’s 2012 young-adult novel, marks a surprisingly original entry in the genre of fanciful mismatched love […]