message: Use Rect for graphics::set_screen_coordinates() param
  Fixes
diff: @@ -699,14 +699,11 @@ pub fn set_point_size(ctx: &mut Context, size: f32) {
  /// be whatever you prefer.
  pub fn set_screen_coordinates(
  context: &mut Context,
  - left: f32,
  - right: f32,
  - top: f32,
  - bottom: f32,
  + rect: Rect,
  ) -> GameResult<()> {
  let gfx = &mut context.gfx_context;
  - gfx.screen_rect = Rect::new(left, bottom, (right - left), (top - bottom));
  - gfx.shader_globals.transform = ortho(left, right, top, bottom, 1.0, -1.0);
  + gfx.screen_rect = rect;
  + gfx.shader_globals.transform = ortho(rect.x, rect.w + rect.x, rect.h + rect.y, rect.y, 1.0, -1.0);
  gfx.update_globals()
  }
  