[erlang-patches] Another xmerl_xpath patch: 'descendant' axis should return nodes in document order

[Matthew Dempsky]

I just realized this patch causes regressions with my earlier patch
for the 'preceding' axis.  I'm currently looking for a comprehensive
XPath test suite, and I'll try to instead submit one large patch (or
at least a handful at once) once I've been able to do that.