Belgian intrastat report

Belgian Intrastat report in 1 module for V8.0
You can replace the iterative search with 2 queries:
- find all ancestors of a given location (including itself) :   
 ```stock_location.search([('parent_left', '<=', loc.parent_left), ('parent_right', '>=', loc.parent_right)]```
- find all warehouses rooted at any of these locations:   
 ```stock_warehouse.search(['lot_stock_id', 'in', loc_ids)]```
Then pick the first one, it should be in the same region.