Root Node & init_root

[aligator]

This adds a root node, and the chunks are spawned as children of it.
You can also add a init_root function to the world configuration:

fn init_root(&self, mut commands: Commands, root: Entity) {
        commands.entity(root).insert((Name::new("physics_world"), Visibility::Hidden));
}

[splashdust]

Looks good to me. Great addition, and nice to have a callback for customising the root entity.
Thanks again for contributing!