Escape arrays sent as binding values for database queries.

Escape arrays sent as binding values for database queries.

Example: trying to select rows from a table where the id is in a given array. In plain SQL this would be:

    SELECT * FROM builds WHERE id IN (1, 2, 3);

Trying to do this using binding values results into an error:

    $ids = array(1, 2, 3);
    $this->db->query("SELECT * FROM builds WHERE id IN ?", array($ids));

Result:

    You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' at line 1

    SELECT * FROM builds WHERE id IN 1

My change will check in `DB_Driver::escape` whether the given parameter is an array. If it is, it will walk the array with `DB_Driver::escape` for each element, therefore escaping it. Finally, it will return the escaped value as "(escaped_id1, escaped_id2, escaped_id3)"

Result:

     SELECT * FROM builds WHERE id IN (1,2,3)  

This also works for string values:

    $ids = array('1', '2', '3');
    $this->db->query("SELECT * FROM builds WHERE id IN ?", array($ids));

Result:

     SELECT * FROM builds WHERE id IN ('1','2','3')  
This would relate more closely to the feature:

    - Added support to binding arrays as ``IN()`` sets in ``query()``.