Added control of threading model, setting default to SingleThreaded to avoid crash  associated with mixing useCursor(false) and multi-threading.
Added control of threading model, setting default to SingleThreaded to avoid crash 
associated with mixing useCursor(false) and multi-threading.


scrawl/osg,marchelbling/osg,tomasthoresen/osg,artoolkit/osg,jtorresfabra/osg,openscenegraph/osg,jtorresfabra/osg,tomasthoresen/osg,artoolkit/osg,jtorresfabra/osg,openscenegraph/osg,scrawl/osg,marchelbling/osg,openscenegraph/osg,marchelbling/osg,artoolkit/osg,tomasthoresen/osg,marchelbling/osg,artoolkit/osg,jtorresfabra/osg,tomasthoresen/osg,openscenegraph/osg,scrawl/osg,scrawl/osg