demos accordingly.
Made OsgCameraGroup set the _applicationUsage to the
osg::ApplicationUsage::instance() when no ArgumentParser is supplied.
Added export to osgProducer::ViewerEventAdapter.
leaving it up to the Viewer to specify the mode (which by default is MultiThreaded).
Added a check for the presence of osgParticle systems so that threading is
disabled in this case.
before state, which fixes problem that can occur with state that needs
the current model view or projection matrices.
Changes osgreflect so that it uses ClipNode rather than clip plane, thereby
fixing the problems which occur when the above is applied.
Create a new osgProducer version of the original GLUT based version.
