Add support for including arbitrary elements to templates

[dnewcome]

We'd like to be able to add some calculated values to the output that don't come from the input XML. For example, recently I used Jath to parse data for use in a Windows Metro application. The application UI is based around items and groups, and when I process my items, I want to assign them to a group, which is a reference to a group object.

Here is an example:

var parsed = Jath.parse( [ '//notes', {
id: 'Note_ID',
title: 'Title',
...
group: pageData.groups[0]
} ], xmldoc );

Jath currently supports using an escape character to insert string literals, but It won't work in the case of something that isn't a string.