Encode a bytearray to a string by converting every byte to a hexadecimal (00 - FF)
representation, and decode the other way around.
author: Johannes Verelst since: MMBase-1.8.1 version: $Id: Hex.java,v 1.5 2007/08/04 08:09:14 michiel Exp $
Transform a string of hexadecimal digits to a bytearray.
Parameters: r - The string to transform an array of bytes throws: IllegalArgumentException - whenever the input string is not correctly formatted.