bugfix-DeepNestingDataGrid

Was getting an error when adding an extended node to a data grid (i.e. QQN::Person()->Project->Location).

It was trying to nest statements, producing code like this:

```php
$str = (($objPerson->Project) ? $objPerson->Project->Location : null)) :  (($objPerson->Project->Location) ? $objPerson->Project->Location : null)->__toString() : null
```
My guess is something changed in PHP to look out for the possibility of a null object being used to call ->__toString(). The new code does something like this:

```php
$str = ($objPerson->Project && $objPerson->Project->Location) : $objPerson->Project->Location->__toString : null;
```