DESCRIPTION:

Find the next voxel matching a given condition.
The command holds internal state defining what "next" means
which is reset by using FINDVOXEL i.
Parameters can be any combination of
- c [classset] which will match for the given classes,
- g from to which will match the given grey range and
- d from to which will match the given depth range.
Giving more than one condition will yield the logic and of
the conditions. Giving the same condition type twice is not
allowed and will give undefined results.