Units
The default-units can be changed by the user.
When you introduce a new unit you have to define:
Be careful with combined units.
It is possible for each user to store a set of preferred units. When creating new b4cast jobs, the user defined units are used by default.
It is possible to reset to original default-units.
When units are user-defined, the relations to the original unit-system are shown on the printed output.