[Dune] How can I read a curved surface from gmsh?

[Dmitry Mikhailovich Mazilkin]

Dear colleagues,

I'm reading a grid from a msh file in the same way, how it 
was in dune-pdelab-tutorials:

     typedef Dune::UGGrid<2> Grid;
     Dune::GridFactory<Grid> factory;
     Dune::GmshReader<Grid>::read(factory,"2d.msh",true,true);
     std::shared_ptr<Grid> gridp(factory.createGrid());

The object I want to read is a curved surface.
Vertices of the grid in msh file have 3 components.
And Z component is meaningful because the surface is not 
flat.
But GmshReader ignores Z coordinates and takes only X and 
Y.

How can I read 2D unstructured grid of curved surface in 
3D space?

Dmitry Mazilkin,
TU Clausthal.