[Xerces-C] SAX2 issues

[Da...@lotus.com]

I think I've found a bug in Xerces-C with regards to SAX2 namespace
handling.  It seems that when SAX2XMLReader calls the registered content
handler with a startElement() event, and that element has no Namespace URI,
the string "EMPTY" is passed, instead of an empty string?  The same thing
happens with attributes that have no namespace URI.  Is this by design?  It
seems very strange and likely non-standard.

I also noticed that SAX2XMLReader does not allowed the registering of
Xerces-specific XMLDocumentHandler instances, even though there is code
throughout that calls any registered readers.  I'd like to fix this and
send the patches in for consideration.

Lastly, I'm wondering if there are any plans to implement SAX2-ext's
LexicalHandler.  This is another piece that Xalan really needs, and I would
be happy to implement.

Dave