SYNOPSIS:
    FIND_COG x y z targetset [sourceset]

DESCRIPTION:
    Fill the connected area starting at x,y,z. If no sourceset is
    given, or it is empty, use the class of the voxel at x/y/z.
    All voxels belonging to sourceset that are connected to x,y,z
    are remarked to targetset.
    The difference to Fillconnected is, that it returns a vector
    with the center of gravity of the found set.

SEE ALSO:
    MARKCC_CONNECTED
