Splittable option in handling unit template

Previously, handling units could always be split. To prevent this, you had to manually clear the Splittable check box in one of the Handling Unit sessions. This took a lot of time and was prone to errors.

Now, the Splittable check box has been added to the Handling Unit Templates (whwmd4160m000) session. The setting of this check box is used by default for all new handling units generated from the template. It is positioned at the Node level, so that it can be decided per handling unit level whether splitting is allowed.