Fixes and features related with Model and Data_Array controller

1. Fix in Model (missing strong comparision).
2. Fix in Data_Array controller in methods deleteAll and getRows.

3. Implement Model->setOrder and Model->setLimit.
4. Grid_Advanced now also call Model->setOrder when sorting by column.
5. Implementation of setOrder in Data_Array controller.
6. Fix for sequential ID generation in Data_Array controller (because of sorting).