new method to find a "real" (ie, not comment or whitespace) xml node

new method to find a "real" (ie, not comment or whitespace) xml node

	* libsoup/soup-misc.c (soup_xml_real_node): new method to find a
	"real" (ie, not comment or whitespace) xml node

	* libsoup/soup-soap-response.c (parse_parameters)
	(soup_soap_response_from_string)
	(soup_soap_parameter_get_first_child)
	(soup_soap_parameter_get_next_child): Use soup_xml_real_node.
	Based on a patch from Andrew W. Nosenko.

	* libsoup/soup-xmlrpc-message.c (soup_xmlrpc_message_from_string):
	don't call xmlKeepBlanksDefault, which changes libxml's behavior
	globally! Instead, use soup_xml_real_node() when traversing the
	xml tree.

	* libsoup/soup-xmlrpc-response.c
	(soup_xmlrpc_response_from_string): don't call
	xmlKeepBlanksDefault.
	(exactly_one_child): rewrite in terms of soup_xml_real_node()
	(which means it handles comments now as well)
	(soup_xmlrpc_value_get_struct)
	(soup_xmlrpc_value_array_get_iterator)
	(soup_xmlrpc_value_array_iterator_prev)
	(soup_xmlrpc_value_array_iterator_next): Use soup_xml_real_node.