Creates get/set methods for the model/properties.
nullobj.defineModel(name, [properties]);
name (string) - model names
optional properties (array) - model properties name/value pairs
The folowing example creates 'cell data model' with two properties - text and color.
obj.defineModel("cell", {text: "", color: "black"});
obj.setCellText("some text")'
var color = obj.getCellColor();
The defineModel() call creates the get/setCellText() and get/setCellColor() methods.