o do regex substitutions on all/any URLs that are encountered,
 which is useful for stripping session IDs from URLs.
 
 <p>This class uses the <tt>urlnormalizer.regex.file</tt> property.
 It should be set to the file name of an xml file which should contain the
 patterns and substitutions to be done on encountered URLs.
 </p>
 <p>This class also supports different rules depending on the scope. Please see
 the javadoc in <A HREF="../../../../../../org/apache/nutch/net/URLNormalizers.html" title="class in org