geometry: rewrite Coordinates trait into a concrete struct, pass coords by reference to shaders, and add a Rectangle type

src/platform/smart_leds_lib.rs

@@ -72,7 +72,7 @@ impl<T: SmartLedsWrite<Color = Rgb<u8>>, S: Surface> Display<S> for SmartLedDisp
             let mut pixel = Rgb::new(0, 0, 0);
             for surface in self.surfaces.iter() {
                 surface.with_shader(|shader| {
-                    pixel = pixel.saturating_add(shader.draw(virt_coords.clone()));
+                    pixel = pixel.saturating_add(shader.draw(&virt_coords));
                 })
             }
             self.total_mw += pixel.as_milliwatts();