HaXml, further updates

[Graham Klyne]

I've done some cleaning up on the code (removing all the old parameter 
entity handling logic in the parser), and fixed a serious known bug in the 
general entity substitution filter (recursive GE definitions would blow the 
stack).  The GE substitution logic has been reorganized to separate the 
various phases.
Some new test cases have been added to the test suite.

The current code is at:
   http://www.ninebynine.org/Software/HaskellUtils/20040628-Haxml-1.12.zip
   http://www.ninebynine.org/Software/HaskellUtils/HaXml-1.12/

There's plenty more that I could do (e.g. see the TODO.txt), but I plan to 
turn my attention to other areas for the foreseeable future.

#g


------------
Graham Klyne
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http://www.ninebynine.org/#Contact