Introduce scale factor for linear dimension entities.

Original request was:

It would be nice to have the possibility to enter dimensions in the form of a formula and still show up as a 'normal' dimension.
This would greatly help in creating details in a different scale (say, 5:1) than the rest of the drawing.
Creating details is quite often necessisary for small objects (when lines are too close together to distinguish at 1:1) if the drawing must be legible to mere humans...

Now one must calculate and manually enter all dimensions for the detail after scaling (and re-calculate every time something gets modified), this is quite error prone.
Exploding the dimensions before scaling is not a real option: the arrowheads and texts then get scaled, too, wich is undesirable.
Scaling back, modifying and then repeating the process is also not quite on the mark: small errors creep in due to finite precision in the calculations made during the scaling.