lib8: implement scale8 from fastled

src/lib8.rs

@@ -2,6 +2,11 @@ use palette::encoding::srgb::Srgb;
 
 use rgb::RGB8;
 
+pub fn scale8(i: u8, scale: u8) -> u8 {
+    // borrowed from FastLED
+    (i as u16 * scale as u16).wrapping_shr(8) as u8
+}
+
 pub trait Rgb8Blend {
     fn saturating_add(self, b: Self) -> Self;
 }