Trite as it certainly sounds, the saccharine label of a “lover letter to cinema” applies all too precisely to French director Arnaud Desplechin’s enchanting docufiction effort “Filmlovers!” (“Spectateurs!”). But even with that obnoxiously overused denomination hanging over it, this multifaceted personal essay succeeds at rekindling or reaffirming one’s own relationship with the miracle of this young art form that we so often take for granted.