closes render window

def close(self):
        """ closes render window """
        # must close out axes marker
        if hasattr(self, 'axes_widget'):
            del self.axes_widget

        # reset scalar bar stuff
        self._scalar_bar_slots = set(range(MAX_N_COLOR_BARS))
        self._scalar_bar_slot_lookup = {}
        self._scalar_bar_ranges = {}
        self._scalar_bar_mappers = {}

        if hasattr(self, 'ren_win'):
            self.ren_win.Finalize()
            del self.ren_win

        if hasattr(self, '_style'):
            del self._style

        if hasattr(self, 'iren'):
            self.iren.RemoveAllObservers()
            del self.iren

        if hasattr(self, 'textActor'):
            del self.textActor

        # end movie
        if hasattr(self, 'mwriter'):
            try:
                self.mwriter.close()
            except BaseException:
                pass