====== Global cell scaling ======
----

With the ''cell_scale'' parameter the unit cells of all reference configurations can be scaled.
This includes box vectors as well as atomic coordinates. Other properties like energy and stress
remain unchanged.

The default value is 1.0, which means no scaling.

Example:

<code potfit config.unscaled>
 #N 4 1
 #C Al
 ## force file generated from file OUTCAR
 #X    4.00000000    0.00000000    0.00000000
 #Y    0.00000000    4.00000000    0.00000000
 #Z    0.00000000    0.00000000    4.00000000
 #W 50
 #E -3.6884100000
 #F
 0           0           0           0           0           0           0
 0           0           2           2           0           0           0
 0           2           0           2           0           0           0
 0           2           2           0           0           0           0
</code>

Using a ''cell_scale'' of 1.5 will result in the following configuration:

<code potfit config.scaled>
 #N 4 1
 #C Al
 ## force file generated from file OUTCAR
 #X    6.00000000    0.00000000    0.00000000
 #Y    0.00000000    6.00000000    0.00000000
 #Z    0.00000000    0.00000000    6.00000000
 #W 50
 #E -3.6884100000
 #F
 0           0           0           0           0           0           0
 0           0           3           3           0           0           0
 0           3           0           3           0           0           0
 0           3           3           0           0           0           0
</code>