Make parser nodes errors actual errors.

(more cleanup will probably be necessary - but this is a start)

nodes/core/parsers/70-XML.js

@@ -40,7 +40,7 @@ module.exports = function(RED) {
                         }
                     });
                 }
-                else { node.log("This node only handles xml strings or js objects."); }
+                else { node.warn("This node only handles xml strings or js objects."); }
             }
         });
     }