Incorrect display of inventory flow for transport dates around the turn of the year

The display of inventory flow under 'Inventory over time' showed incorrect quantities when the transport date was around the turn of the year. A transport date of 31-12 can fall in week 1 of the following year, and the calculations must be able to handle this. In this display, for transport dates around the turn of the year, the correct month and year will now always be shown.