Mapping the "value" field in the JSON data driver

The JSON data driver has an option to map the object property that stores the children; i.e. data → cars in [custom JSON format for trees](http://docs.webix.com/datatree__data_formats.html#customjsonformat example.

A nice feature: ability to map the “value” field as well. Kendo provides that with the dataTextField property.

The only predefined attributes are id and data. All other can be configured through templates.

http://webix.com/snippet/97f3105f

Templates are more powerful, thanks.