message: have "--no-plane" option avoid adding the plane at all instead of hiding it
diff: @@ -250,7 +250,6 @@ static inline void addPlaneToScene(sg::Node& renderer)
  index->setName("index");
  auto &plane = world.createChild("plane", "Instance");
  - plane["visible"].setValue(addPlane);
  auto &mesh = plane.child("model").createChild("mesh", "TriangleMesh");
  auto sg_plane = mesh.nodeAs<sg::TriangleMesh>();
  @@ -434,7 +433,7 @@ int main(int ac, const char **av)
  addLightsToScene(renderer);
  addImporterNodesToWorld(renderer);
  addAnimatedImporterNodesToWorld(renderer);
  - if (!no_defaults)
  + if (!no_defaults && addPlane)
  addPlaneToScene(renderer);
  // last, to be able to modify all created SG nodes
  