146 Compatibility issue: SoShapeHints::windingType missing in Coin.

    This was added for TGS OIV 4.0, so we should implement this for
    compatibility reasons. We've also had an external request for
    supporting polygons with holes, which this field is the public API
    for doing.

    pederb suggests using GLU for tessellating such polygons, as
    adding that capability to SbTesselator is a non-trivial task.

    Note that this breaks ABI-compatibility, so it is only relevant
    for Coin 3.

    20041010 mortene.

    UPDATE 20041210 mortene: GLU tessellation can do polygons with
    holes, and we should probably use that for the implementation of
    this feature.

    UPDATE 20041213 kintel: The MS Windows implementation of GLU
    is known to be buggy (it crashes AFAIR) wrt. tesselating polygons
    with holes.

    UPDATE 20050809 mortene: adding the capability of tessellating
    polygons with holes to SbTessellator would perhaps be a good task
    for a student. Suggested by pederb.

    UPDATE 20060216 mortene: I've now added an abstraction layer on
    top of the GLU tessellation functionality, which resembles our own
    SbTesselator -- for convenience. See src/base/SbGLUTessellator.h.

    Implementing support for the windingType field should be quite
    straightforward now.
