feat(renderer): a matte variant of a material for the parts of rails no wheel rolls on: it lights the same maps as weathered steel, with the weathering scaled per vertex by userdata, so a polished running surface fades into unused steel without a bright stripe; the cut faces of rails are drawn in it in an extra pass

rendering/opengl33renderer.h

@@ -78,6 +78,8 @@ class opengl33_renderer : public gfx_renderer {
     // material methods
     material_handle
         Fetch_Material( std::string const &Filename, bool const Loadnow = true ) override;
+    material_handle
+        Matte_Material( material_handle const Material ) override;
     void
         Bind_Material( material_handle const Material, TSubModel const *sm = nullptr, lighting_data const *lighting = nullptr ) override;
     IMaterial const *