message: Remove unused PackedVertex struct
  All references to `PackedVertex` were removed in so there is no
  reason to keep it around.
diff: @@ -450,12 +450,6 @@ pub struct LoaderApi<'a> {
  current_atlas: &'a mut usize,
  }
  -#[derive(Debug)]
  -pub struct PackedVertex {
  - x: f32,
  - y: f32,
  -}
  -
  #[derive(Debug, Default)]
  pub struct Batch {
  tex: GLuint,
  