Implement XMLTOCURSOR()

[Irwin1985]

Implements XMLTOCURSOR().

The data is always read with XmlReadMode.InferSchema which hands every column over as a string and the inline XSD is read separately with XPath.

[RobertvanderHulst]

A small styling comment: I personally do not like the long list of functions that start with __FoxXml.
I understand that you choose the prefix to group them together.
Our Functions classes are already very full with methods and defines. Since this is an internal implementation I would like to move this to a separate class. I have done something similar for the OOPHelpers class in XSharp.RT.
So I suggest that create an (internal) class FoxXml or something similar and make these all methods of the same class. That way they are grouped together. You can also add the defines as constants to the class.

[Irwin1985]

Robert, my fault. I remember you told me this before. I'll create a note in my desktop to memorize it because I do use this convention in daily work.

I'll do the refactor ASAP.