Finds a child by name and returns it.

If no child with name can be found, null is returned. If name contains a '/' character it will traverse the hierarchy like a path name.

	// The magical rotating finger
	function Update() {
		aFinger = transform.Find("LeftShoulderArmHand/Finger");
		aFinger.Rotate(Time.deltaTime*20, 0, 0);
	}