An method for setting GuidReference target object from editor tools could be useful

[schmid]

Adding this to GuidReference.cs is useful for editor tools:

#if UNITY_EDITOR
    public void SetReferenceEditor(MonoBehaviour behaviourWithReference, GuidComponent target)
    {
        Undo.RecordObject(behaviourWithReference, "Set GUID Reference");
        guid = target.GetGuid();
    }
#endif