a Color object or null if the string's length is invalid
ConvException if one of the string is not an hexadecimal number
assert(Color.fromString("00CC00").green == 204); assert(Color.fromString("123456").rgb == 0x123456); assert(Color.fromString("01F") == Color.fromString("0011FF"));
Converts and hexadecimal representation of a colour into a Color object.