Various little fixes (#118)

* Add missing override qualifier

* Mostly shadowing, virtual destructor and other little things

include/Nazara/Utility/Joint.hpp

@@ -35,7 +35,7 @@ namespace Nz
 			void SetName(const String& name);
 
 		private:
-			void InvalidateNode();
+			void InvalidateNode() override;
 			void UpdateSkinningMatrix() const;
 
 			Matrix4f m_inverseBindMatrix;