Enable per-frame light list updates (Bug #2638, Bug #2654)

The performance impact isn't so big anymore since the last commit.

components/sceneutil/lightmanager.cpp

@@ -274,16 +274,6 @@ namespace SceneUtil
 
         if (lights.size())
         {
-
-            static std::map<osg::Node*, osg::ref_ptr<osg::StateSet> > statesets;
-            std::map<osg::Node*, osg::ref_ptr<osg::StateSet> >::iterator found = statesets.find(node);
-            osg::ref_ptr<osg::StateSet> stateset;
-            if (found != statesets.end())
-            {
-                stateset = found->second;
-            }
-            else{
-
             // we do the intersections in view space
             osg::BoundingSphere nodeBound = node->getBound();
             osg::Matrixf mat = *cv->getModelViewMatrix();
@@ -299,7 +289,6 @@ namespace SceneUtil
 
             if (lightList.empty())
             {
-                    statesets[node] = NULL;
                 traverse(node, nv);
                 return;
             }
@@ -316,16 +305,12 @@ namespace SceneUtil
                     lightList.pop_back();
             }
 
-                stateset = mLightManager->getLightListStateSet(lightList);
-                statesets[node] = stateset;
-            }
+            osg::StateSet* stateset = mLightManager->getLightListStateSet(lightList);
 
-            if (stateset)
             cv->pushStateSet(stateset);
 
             traverse(node, nv);
 
-            if (stateset)
             cv->popStateSet();
         }
         else