stock_usability: Add computed field is_dropship (needed to customize some reports)

Add optional fields in stock.move tree view

stock_usability/models/__init__.py

@@ -1,6 +1,7 @@
 from . import stock_move
 from . import stock_move_line
 from . import stock_picking
+from . import stock_picking_type
 from . import stock_warehouse_orderpoint
 from . import stock_quant
 from . import procurement_group