Converted AnimationPath so it is now subclassed from osg::Transform::ComputeTransfromCallback()
so that it can be directly attached to the scene to move objects about.
Changed the osg::SateSet::setGlobalDefaults() so that is sets GL_DEPTH_TEST
to ON.
Added guards and creation of default helper classes in osgGLUT::Viewer and
osgUtil::SceneView so that sensible defaults are used when no settings
are used of osg::State/StateSet,osgUtil::RenderStage/RenderGraph/CullVisitor.
and have updated GeoSet to use mutable values for the _numverts etc, allowing
osg::GeoSet::computeNumVerts() to be a const operation. osg::GeoSet::getNumVerts
is now a const once more, so avoiding compilation problems. Also chaned the new
osgconv orientation code to use a Drawable::AttributeFunctor so it can work on
other Drawables other than just GeoSets.
