fixed an erroneous validation bug when PE refs occurs in external parsed

* parser.c: fixed an erroneous validation bug when PE refs
  occurs in external parsed entities referenced from the
  internals subset
* test/valid/index.xml test/valid/dtds/nitf-2-5.dtd
  test/valid/dtds/NewsMLv1.0.dtd result/valid/index.xml*:
  added the associated testcase, it's a nice one.
* HTMLparser.c: generate the DTD node as HTML still ...
* HTMLtree.c: fixed errors in Set/GetMetaEncoding
Daniel
12 files changed