move ColorFromHSL out of the ui code

OpenRA.FileFormats/PlayerColorRemap.cs

@@ -46,5 +46,34 @@ namespace OpenRA.FileFormats
 			return remapColors.TryGetValue(index, out c) 
 				? c : original;
 		}
+
+		// hk is hue in the range [0,1] instead of [0,360]
+		public static Color ColorFromHSL(float hk, float s, float l)
+		{
+			// Convert from HSL to RGB
+			var q = (l < 0.5f) ? l * (1 + s) : l + s - (l * s);
+			var p = 2 * l - q;
+
+			float[] trgb = { hk + 1 / 3.0f,
+							  hk,
+							  hk - 1/3.0f };
+			float[] rgb = { 0, 0, 0 };
+
+			for (int k = 0; k < 3; k++)
+			{
+				while (trgb[k] < 0) trgb[k] += 1.0f;
+				while (trgb[k] > 1) trgb[k] -= 1.0f;
+			}
+
+			for (int k = 0; k < 3; k++)
+			{
+				if (trgb[k] < 1 / 6.0f) { rgb[k] = (p + ((q - p) * 6 * trgb[k])); }
+				else if (trgb[k] >= 1 / 6.0f && trgb[k] < 0.5) { rgb[k] = q; }
+				else if (trgb[k] >= 0.5f && trgb[k] < 2.0f / 3) { rgb[k] = (p + ((q - p) * 6 * (2.0f / 3 - trgb[k]))); }
+				else { rgb[k] = p; }
+			}
+
+			return Color.FromArgb((int)(rgb[0] * 255), (int)(rgb[1] * 255), (int)(rgb[2] * 255));
+		}
 	}
 }