Added a local implementation of SlideEventHandler::checkNeedToDoFrame() so that Present3D can toggle on/off the need for continuous rendering to only slides that require it,

enabling slides with no animation to sit iddle rather keeping rendering, reducing CPU/GPU overhead and saving power.

include/osgPresentation/SlideEventHandler

@@ -344,6 +344,7 @@ public:
 
     osg::Switch* getPresentationSwitch() { return _presentationSwitch.get(); }
 
+
     enum WhichPosition
     {
         FIRST_POSITION = 0,
@@ -405,6 +406,8 @@ public:
 
     double getReferenceTime() const { return _referenceTime; }
 
+    virtual bool checkNeedToDoFrame();
+
 protected:
 
     ~SlideEventHandler() {}