message: Add `SpriteBatch::image()`
diff: @@ -160,6 +160,11 @@ impl SpriteBatch {
  mem::replace(&mut self.image, image)
  }
  + /// Returns a reference to the spritebatch's image.
  + pub fn image(&self) -> &graphics::Image {
  + &self.image
  + }
  +
  /// Get the filter mode for the SpriteBatch.
  pub fn filter(&self) -> FilterMode {
  self.image.filter()
  