Replace Kiss3d by Bevy for the testbed renderer.

examples2d/joints2.rs

@@ -68,8 +68,3 @@ pub fn init_world(testbed: &mut Testbed) {
     testbed.set_world(bodies, colliders, joints);
     testbed.look_at(Point2::new(numk as f32 * rad, numi as f32 * -rad), 20.0);
 }
-
-fn main() {
-    let testbed = Testbed::from_builders(0, vec![("Joints", init_world)]);
-    testbed.run()
-}