Updated XML handling a bit

I noticed when i pulled down the project, built nustache.exe, and executed the test template against the test xml, the xml values were not substituted properly. I tried to improve this. Please let me know what you think and integrate if you'd like to. Thanks very much! More details below

Templating 
> nustache.exe test.nustache test.xml foo.txt

Output
> type foo.txt
Hello
You have just won $System.Xml.XPathNodeList!
!!!


In my change
<x>
<d>a</d>
<d>b</d>
</x>

{{#d}}
{{.}}
{{/d}

would render     a  b

<x>
<c>text</c>
</x>

{{c}}

would render    text

And test template renders

Hello Chris
You have just won $10000!
Well, $9600, after taxes.
!!!