Improve/safety

- Adds a new delegate:

```objc
- (void)dataSource:(ANDYFetchedResultsTableDataSource *)dataSource
     didMoveObject:(NSManagedObject *)object
     withIndexPath:(NSIndexPath *)indexPath newIndexPath:(NSIndexPath *)newIndexPath;
```

Support hidden controllers:
```
@property (nonatomic) BOOL parentControllerIsHidden;
```