adds XPath support to XML::DOM, using XML::XPathEngine

 XML::DOM::XPath allows you to use XML::XPath methods to query a DOM.
 This is often much easier than relying only on getElementsByTagName.
 It lets you use all of the XML::DOM methods.
 .
 In truth this should only be used if you have existing code using XML::DOM.
 If you start a new project and you can install XML::LibXML (and libxml2 on
 which it is based) then you will get a DOM, XPath support and a lot more
 power and speed.