[FIX] point_of_sale: the product name field changed to display_name to include variants information, this should be reflected in searches as well.
[FIX] point_of_sale: the order uid were generated via timestamp, which were not sequencial or easy to understand, they are now generated with the order id and order sequence number which are sequencial
[FIX] point_of_sale: invoicing in the pos printed the wrong order due to a mismatch between order ids and invoice ids
[IMP] models: improve code of _convert_to_write(), make it easier to read