This module parses /robots.txt files as specified in "A Standard for
Robot Exclusion", at <http://www.robotstxt.org/wc/norobots.html>
Webmasters can use the /robots.txt file to forbid conforming robots
from accessing parts of their web site.
The parsed files are kept in a WWW::RobotRules object, and this
object provides methods to check if access to a given URL is
prohibited. The same WWW::RobotRules object can be used for one
or more parsed /robots.txt files on any number of hosts.