iXML grammars for XPath/XQuery4

As shown at the 2024sep24 meeting, grammars for the current draft of 
XPath and XQuery 4.0 in iXML format, suitable for experimentation, are 
now available from 
https://github.com/johnlumley/jwiXML/tree/main/QT4Grammars, and via an 
interactive iXML workbench at https://johnlumley.github.io/jwiXML.xhtml

They have been exercised over the 35k expressions in the QT4 test suite, 
and have about 50 cases of failure and some 200 cases of explainable 
ambiguity - see the README for further explanation.

John

-- 
*John Lumley* MA PhD CEng FIEE
john@saxonica.com