get_accessible_at
Description:
Gets the table cell at the specified row and column indices.
To get the accessible object at a particular (x, y) screen coordinate, use get_accessible_at_point.
Parameters:
| this | a pointer to the Table implementor on which to operate. | 
| row | the specified table row, zero-indexed. | 
| column | the specified table column, zero-indexed. | 
Returns:
| an Accessible object representing the specified table cell. |