[libxml++] Unknown encoding crashes DOM Parser

[<p....@ic...>]

The following encoding
      <?xml version="1.0" encoding="ISO-8859-15"?>
leads to a crash under Windows and Linux.

In domparser.cc / DomParser::parse_context() one finds:

xmlParseDocument(_context);
_doc = new Document(_context->myDoc); // context->myDoc is 0 if encoding is
illegal, therefore the constructor segfaults

It should be checked if _context->myDoc is a valid pointer.

Best regards, Peter.