refresh the current object for any command which does not select another object

I am unsure about this one, because it could be both useless (if the current object was not modified) AND expensive (e.g. if the current object is a remote object), but I think it would help more often than not.

```python
def update():
    arr['a1'] = 0

arr = ndtest((2, 3))
```
(arr appears like it should)

```python
update()
```

(arr is not updated)