Add new state before packing in shipment out workflow
Following discuss https://discuss.tryton.org/t/customer-shipments-and-packing/3228
It seems necessary to add a new workflow step to sync inventory moves before packing in shipment out process.
Indeed, currently you can rely your packages to outgoing moves but when doing this process those moves are not synced with your inventory moves, so it's impossible to link a package with a lot, or with a splitted quantity, ... (or you have to updated first manually your outgoing moves)
Solution would be adding an extra step that will sync inventory moves with outgoing moves and then allow you to tell correctly which move is on which package to have a correct packing list and then you can do the shipment.
So there'll be a new "picked" state after "assigned" and before "packed".