add streaming on memory regression tests, found bad bugs in the reader

* Makefile.am: add streaming on memory regression tests, found
  bad bugs in the reader interface
* xmlreader.c: fixing bugs w.r.t. very large names, and special
  condition in end of file.
* xmlIO.c tree.c include/libxml/tree.h include/libxml/xmlIO.h:
  adding immutable buffers, and parser input based on those,
  but this should not be used (yet) for general parsing
* parser.c: added a comment about using immutable buffers for
  general parsing.
* result/bigname.xml.rdr result/bigname2.xml.rdr: fixing the
  output of the regression tests
* xmllint.c: using the immutable buffers when streaming on
  mmaped file (--stream --memory)
Daniel

parser.c

@@ -11568,6 +11568,7 @@ xmlCreateMemoryParserCtxt(const char *buffer, int size) {
     if (ctxt == NULL)
 	return(NULL);
 
+    /* TODO: xmlParserInputBufferCreateStatic, requires some serious changes */
     buf = xmlParserInputBufferCreateMem(buffer, size, XML_CHAR_ENCODING_NONE);
     if (buf == NULL) {
 	xmlFreeParserCtxt(ctxt);