From “The Revenant” to “The Martian,” why do so many of this year’s most celebrated films hark back to a genre we thought was long gone — the Western? Plus, we hit the streets of Boston to find out why so many actors find a certain Northeastern accent so hard to pull off. Wendell Pierce of “The Wire” and “Selma” gives the Academy some pointers to fix their #OscarsSoWhite problem. And we finally find out what the heck a gaffer does.