rem: gchar * child_content ( xmlDocPtr node, gchar * child_name )
add: gchar * child_content ( xmlNodePtr node, gchar * child_name )
context: gchar * child_content ( xmlDocPtr node, gchar * child_name ){  xmlDocPtr child_node;  if (!node) return NULL;  child_node = get_child ( node, child_name );  if ( child_node )    return xmlNodeGetContent ( child_node );    return NULL;}