Updated XPath spec

I've updated the XPath draft at

https://qt4cg.org/branch/master/xquery-40/xpath-40-diff.html

There's a substantial reorganisation of the material on functions to try and get it into a more logical order, and the treatment of arity ranges is now much more detailed.

I also added a proposal for non-ASCII mathematical operators as optional alternatives to keywords like div and gt. (I fear this could become a bit of a bicycle shed, though...)

Let me know what you think.

If you raise an issue on Github, it's more likely to be followed through to a conclusion than unstructured conversations on email.

Michael Kay
Saxonica