SYNOPSIS:
    MARKCC_DILATE size [fromset] [toset] [onlyto]

DESCRIPTION:
    Dilate fromset by size. The newly created voxels (the border)
    is colored according to toset. If "onlyto" is given, only
    voxels from this set are available for expansion.
    Note: This filter is implemented as a separated filter.
    This may lead to unexpected behaviour, if onlyto is used.
