Expedition lines from same orderline merged.

When there are more expedition lines from same orderline key, merge them
and get source warehouses. Usefull future possibility for creating
shippinglines with same products from multiple warehouses.
@KreizIT also changed some batch related items.
Fix deliveryorder qty and remainingqty positions
Fix migration sql for inserting accounting records

Migration SQL could not insert accounting records because datec was set
to NOT NULL
Merge pull request #1937 from fappels/develop

Expedition lines from same orderline merged.