Shader animation bug is fixed.

Changed the conditions when unsubscribes the shader animation events.
Or it will unsubcribe all the events if you call SetShaderParameterAnimation function twice. (For example, you need to animate texture U and V )

Source/Urho3D/Graphics/Material.cpp

@@ -1235,7 +1235,7 @@ void Material::UpdateEventSubscription()
             SubscribeToEvent(E_UPDATE, URHO3D_HANDLER(Material, HandleAttributeAnimationUpdate));
         subscribed_ = true;
     }
-    else if (subscribed_)
+    else if (subscribed_ && shaderParameterAnimationInfos_.Empty())
     {
         UnsubscribeFromEvent(E_UPDATE);
         UnsubscribeFromEvent(E_ATTRIBUTEANIMATIONUPDATE);