Add hex methods for RGB, packed format for u32 RGB

Add into_hex and from_hex methods for RGB and RGBA
Implement packed RGBA structs with representations
    - RGBA
    - ARGB
    - BGRA
    - ABGR

palette/src/lib.rs

@@ -176,7 +176,10 @@ pub use hwb::{Hwb, Hwba};
 pub use lab::{Lab, Laba};
 pub use lch::{Lch, Lcha};
 pub use luma::{GammaLuma, GammaLumaa, LinLuma, LinLumaa, SrgbLuma, SrgbLumaa};
-pub use rgb::{GammaSrgb, GammaSrgba, LinSrgb, LinSrgba, Srgb, Srgba};
+pub use rgb::{
+    GammaSrgb, GammaSrgba, LinSrgb, LinSrgba, PackedAbgr, PackedArgb, PackedBgra, PackedRgba, Srgb,
+    Srgba,
+};
 pub use xyz::{Xyz, Xyza};
 pub use yxy::{Yxy, Yxya};
 

palette/src/rgb/mod.rs

@@ -6,9 +6,10 @@ use crate::encoding::{self, Gamma, Linear, TransferFn};
 use crate::white_point::WhitePoint;
 use crate::{Component, FloatComponent, FromComponent, Yxy};
 
+pub use self::packed::{PackedAbgr, PackedArgb, PackedBgra, PackedRgba};
 pub use self::rgb::{Rgb, Rgba};
 
-//mod linear;
+mod packed;
 mod rgb;
 
 /// Nonlinear sRGB.