The Skung Rockification of Ziggy Skungdust and the SIMD's

Sources/JolkEngine/Colour.swift

@@ -42,6 +42,11 @@ public extension Colour
 			a: Float((fromRgba32 >>  0) & 0xFF) / 0xFF)
 	}
 
+	init(grey v: Float)
+	{
+		self.init(r: v, g: v, b: v)
+	}
+
 	func mix(with rhs: Colour, _ amount: Float) -> Colour
 	{
 		let x = amount.saturate