Foreign Object ID

[tpodhraski]

Add the official way to work with foreign keys, managed object context should have a list of "friend" contexts associated by a name. This way we can add more safety to models that do this kind of behavior. How this would look:

    public class ForeignObjectId extends ManagedObjectId 
    {
        private var _contextId:String;
        // Implement get and set, override some methods
    }

    managedContext.registerForeignContext("other", otherContext);