SYNOPSIS:
    MARKCC_HALFDILATE1D axismask size [fromset] [toset] [onlyto]

DESCRIPTION:
    Dilate fromset by size along the given halfaxes.
    The newly created voxels (the border) are colored according to
    toset. If "onlyto" is given, only voxels from this set are
    available for expansion.
    The axismask is a bitmask consisting of:
     1 positive X axis
     2 negative X axis
     4 positive Y axis
     8 negative Y axis
    16 positive Z axis
    32 negative Z axis
    The processing steps are separated. This may lead to unexpected
    behaviour, if multiple axis are used at once. The filter will
    run in the order z,y,x.
