DESCRIPTION:

Dilate fromset by size towards the positive axis.
The newly created voxels (the border) is colored according to
toset. If "onlyto" is given, only voxels from this set are
available for expansion. Due to the asymmetric nature of that
filter, it is only recommended to be used for size=1 to get
a slight thinkening below what MARKCC_DILATE can do.
Note: This filter is implemented as a separated filter.
This may lead to unexpected behaviour, if onlyto is used.