message: Adds type for boxed ShaderHandle on shader.rs
  This has to do with a complex type warning. The type was also used on L256.
diff: @@ -188,6 +188,8 @@ pub struct ShaderGeneric<Spec: graphics::BackendSpec, C: Structure<ConstFormat>>
  /// with a ggez graphics context
  pub type Shader<C> = ShaderGeneric<graphics::GlBackendSpec, C>;
  +type ShaderHandlePtr<Spec> = Box<dyn ShaderHandle<Spec>>;
  +
  pub(crate) fn create_shader<C, S, Spec>(
  vertex_source: &[u8],
  pixel_source: &[u8],
  @@ -199,7 +201,7 @@ pub(crate) fn create_shader<C, S, Spec>(
  blend_modes: Option<&[BlendMode]>,
  color_format: format::Format,
  debug_id: DebugId,
  -) -> GameResult<(ShaderGeneric<Spec, C>, Box<dyn ShaderHandle<Spec>>)>
  +) -> GameResult<(ShaderGeneric<Spec, C>, ShaderHandlePtr<Spec>)>
  where
  C: 'static + Pod + Structure<ConstFormat> + Clone + Copy,
  S: Into<String>,
  @@ -251,7 +253,7 @@ where
  psos,
  active_blend_mode: blend_modes[0],
  };
  - let draw: Box<dyn ShaderHandle<Spec>> = Box::new(program);
  + let draw: ShaderHandlePtr<Spec> = Box::new(program);
  let id = 0;
  let shader = ShaderGeneric {
  