Shadows,fixed an issue when PolyOffset was not properly applied on lighting material

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@10044 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core-data/Common/MatDefs/Light/Lighting.j3md

@@ -188,7 +188,7 @@ MaterialDef Phong Lighting {
             DISCARD_ALPHA : AlphaDiscardThreshold
         }
 
-        RenderState {
+        ForcedRenderState {
             FaceCull Off
             DepthTest On
             DepthWrite On