Allow to filter on a list of values via a query with "IN".

Hi,

Something I need often: a way to filter values by a list. There are many cases where this is useful, for example, to get only some options:
```php
get_table_options('ItemType', null, array(
    'name' => array(
        'Text',
        'Still Image',
        'Event',
        'Physical Object',
    ),
)); 
```

Sincerely,

Daniel Berthereau
Infodoc & Knowledge management