DESCRIPTION:

Do a filling operation based on breadth first search which
is tolerant to faulty borders containing gaps.
The parameters for the BFS function are not all specified
on the commandline, as they are changed rarely between fill
operations. Instead the following variables influence the
behaviour of th BFS command:
/module.internal.bfs.distance/ sets the maximum allowed
    hole size. That is, holes of a diameter of less than the
    value given here will not cause the fill operation to spill
    out.
/module.internal.bfs.pocketsize/ sets the maximum size
    allowed for "pockets" that might be behind a hole of the above
    diameter. Reasonable values are about (2*distance)^2.
/module.internal.bfs.pocketloops/ sets how many attempts
    are made to fill side channels that are caused by such
    pockets. Reasonable values range from 0-10 with 3 being a
    good default value.
/module.internal.bfs.pocketdepth/ sets the maximum depth
    allowed for "pockets" that might be behind a hole of the above
    diameter. Reasonable values are about 2*dist.
    Note, that this differs from pocketsize. Pocketdepth cares
    about how long a structure is, while pocketsize cares about
    what area the cross-sections of the structure with the
    elementary planes cover.
/module.internal.bfs.fillcolor/ sets the color that is
    used for BFS filling. This defaults to 6 (yellow) for historical
    reasons. If set to -1, BFS will behave like most other commands
    and use the colorize setting of the current view.
    This can be controlled idependently, as one will often want to
    use another color for drawing barriers to stop spillout, if
    large gaps exist.