does not work as expected for Viewport and Blender Internal. As @sergey noticed, this was caused by rBfbf8595, which disabled rendering for wireframe objects in the viewport. However, the same function `is_object_hidden` is also used for skipping dupli objects then which may themselves be renderable. Now use two variants: * is_object_restricted is the previous test for general viewport/render visibility (lets wireframe duplicators pass) * is_object_hidden includes the wireframe check for actual render instances