Description:
------------
I think we need to be able to allow traits to require that the class in which it can be used must be an instance of an arbitrary class/interface.

Expected result:
----------------
trait AirConditioning requires Vehicle
{
    public function increaseTemperature() { $this->ambientTemperature++; }
    public function decreaseTemperature() { $this->ambientTemperature--; }
}

abstract class Vehicle
{
    protected $ambientTemperature;
}

class Car extends Vehicle {}
class Truck extends Vehicle {}
class Dog extends Animal {}

class MyOldCar extends Car {}
class MyNewCar extends Car
{
    use AirConditioning; // Should be OK
}

class MyLabrador extends Dog
{
    use AirConditioning; // Should throw an exception
}