ACTION-2027: Decide how to deal with adjust-datetime-to-timezone() clash

All,

This one is done. Text:


https://www.w3.org/community/xformsusers/wiki/XPath_Expressions_Module#The_adjust-dateTime-to-timezone.28.29_Function

Diff:


https://www.w3.org/community/xformsusers/wiki/index.php?title=XPath_Expressions_Module&diff=228&oldid=226

I used text similar to `seconds-from-dateTime()`, except the recommendation
is to use the XPath 2 function. I haven't provided an alternate name for
this function. Like with `seconds-from-dateTime()`, the legacy XForms
function is placed in a different namespace depending on whether we are in
XPath 2.0 mode or in XPath 1.0 backwards-compatibility mode.

-Erik