message: Add set_filter() and get_filter() function for SpriteBatch
diff: @@ -14,6 +14,7 @@ use gfx;
  use gfx::Factory;
  use GameResult;
  use super::shader::BlendMode;
  +use super::types::FilterMode;
  /// A `SpriteBatch` draws a number of copies of the same image, using a single draw call.
  ///
  @@ -143,6 +144,16 @@ impl SpriteBatch {
  mem::replace(&mut self.image, image)
  }
  + /// Get the filter mode for the SpriteBatch.
  + pub fn get_filter(&self) -> FilterMode {
  + self.image.get_filter()
  + }
  +
  + /// Set the filter mode for the SpriteBatch.
  + pub fn set_filter(&mut self, mode: FilterMode) {
  + self.image.set_filter(mode);
  + }
  +
  /// Create an object which draws the current sprite batch with a different image.
  #[deprecated]
  #[allow(deprecated)]
  