Make backface culling ready to use

src/main.rs

@@ -94,6 +94,8 @@ fn main() {
                 write: true,
                 ..Default::default()
             },
+            // Verify that it helps from the FPS point of view.
+            //backface_culling: glium::draw_parameters::BackfaceCullingMode::CullClockwise,
             ..Default::default()
         };