many further little changes for OOM problems. Now seems to be getting

* SAX2.c, encoding.c, error.c, parser.c, tree.c, uri.c, xmlIO.c,
  xmlreader.c, include/libxml/tree.h: many further little changes
  for OOM problems.  Now seems to be getting closer to "ok".
* testOOM.c: added code to intercept more errors, found more
  problems with library. Changed method of flagging / counting
  errors intercepted.

encoding.c

@@ -1263,6 +1263,7 @@ xmlNewCharEncodingHandler(const char *name,
     handler = (xmlCharEncodingHandlerPtr)
               xmlMalloc(sizeof(xmlCharEncodingHandler));
     if (handler == NULL) {
+        xmlFree(up);
         xmlGenericError(xmlGenericErrorContext,
 		"xmlNewCharEncodingHandler : out of memory !\n");
 	return(NULL);