Arr helper forwarding calls to Illuminate Arr helper fails for methods with array passed by reference

[lindyhopchris]

At the moment the LaravelJsonApi\Core\Support\Arr helper forwards static calls through to the Illuminate\Support\Arr class. This does not work for methods, e.g. forget, where the array is passed by reference. To fix, we will need to implement these methods on our Arr class and mark the value as passed by reference: then forward on to the correct method in the Illuminate class.

[lindyhopchris]

Think the best option here is to deprecate forwarding the calls, then remove the forwarding.