[csharp] Fixed "rgb2" timeline "light" color failing to read when hav…

…ing hexstring length 8 instead of 6. Closes EsotericSoftware#2476.

spine-csharp/src/SkeletonJson.cs

@@ -1232,8 +1232,8 @@ static string GetString (Dictionary<string, Object> map, string name, string def
 		}
 
 		static float ToColor (string hexString, int colorIndex, int expectedLength = 8) {
-			if (hexString.Length != expectedLength)
-				throw new ArgumentException("Color hexidecimal length must be " + expectedLength + ", recieved: " + hexString, "hexString");
+			if (hexString.Length < expectedLength)
+				throw new ArgumentException("Color hexadecimal length must be " + expectedLength + ", received: " + hexString, "hexString");
 			return Convert.ToInt32(hexString.Substring(colorIndex * 2, 2), 16) / (float)255;
 		}
 	}