Use default parameters where appropriate

apps/openmw/mwclass/light.cpp

@@ -38,7 +38,7 @@ namespace MWClass
         if (!model.empty())
             objects.insertMesh(ptr, "meshes\\" + model, true);
         else
-            objects.insertLight(ptr, NULL, Ogre::Vector3(0,0,0));
+            objects.insertLight(ptr);
     }
 
     void Light::insertObject(const MWWorld::Ptr& ptr, MWWorld::PhysicsSystem& physics) const

apps/openmw/mwrender/objects.hpp

@@ -74,7 +74,7 @@ public:
     ~Objects(){}
     void insertBegin (const MWWorld::Ptr& ptr, bool enabled, bool static_);
     void insertMesh (const MWWorld::Ptr& ptr, const std::string& mesh, bool light=false);
-    void insertLight (const MWWorld::Ptr& ptr, Ogre::Entity* skelBase, Ogre::Vector3 fallbackCenter);
+    void insertLight (const MWWorld::Ptr& ptr, Ogre::Entity *skelBase=0, Ogre::Vector3 fallbackCenter=Ogre::Vector3(0.0f));
 
     void enableLights();
     void disableLights();