When “Mustang” opened to a small handful of U.S. theaters last year, critics gushed. But like many independent films, it evaporated at cinemas like an ice cube on a hot stove. When it showed up on Amazon recently, I was ecstatic and planned an evening to watch it with my husband and teen aged daughter. From the opening scene to the end credits, we were totally engrossed. Charmed and repelled. Happy and incredulous. Our hearts broke. The good news is that “Mustang” has a good