Stock Usability

The usability enhancements include: * display the source location on the tree view of the move lines of the pickings (by default, only the destination location is displayed). * always display the field Backorder on the form view of picking (by default, this field is only displayed when it has a value, so the user doesn't know when the field has no value because he doesn't see the field !) * add a group by Partner in the picking search view (particularly usefull for receptions) * add graph view for pickings * remove ability to translate stock.location, stock.location.route and stock.picking.type

This module has been written by Alexis de Lattre from Akretion <alexis.delattre@akretion.com>.