This class is used to create handlers for child elements based on the
currently defined namespaces. This class is called by the XMLSAXHandler to
help act as a library of prefix -> Schema mappings.
Creates an element handler for the element specified by name and
namespace. Will return null if a suitable handler is not found.
Parameters: namespaceURI - Parameters: localName - throws: SAXException - See Also:ElementHandlerFactory.createElementHandler(Element)