bigname.xml.rdr

* 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