Added osg::FrameStamp::set/getSimulationTime().

Added setting of osg_SimulationTime and osg_DeltaSimulationTime to the uniforms set by SceneView

Added frame(double simulationTime) and advance(double simulationTime) parameters to
osgViewer::SimpleViewer, Vewer and CompositeViewer.

Updated various examples and Nodes to use SimulationTime where appropriate.

src/osg/Sequence.cpp

@@ -127,7 +127,7 @@ void Sequence::traverse(NodeVisitor& nv)
         if (framestamp)
         {
     
-            double t = framestamp->getReferenceTime();
+            double t = framestamp->getSimulationTime();
             if (_last == -1.0)
                 _last = t;