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.
handle scenes with multiple views with elements that need coordinating on a per view basis.
Added beginings of new osgText::FadeText class (not functionality yet).