[dune-fem] Lagrange DG extract points

[Agnese, Marco]

Hi,
I have a function f:x_global->y_global and I want to evaluate it in all the degree of freedom of a certain DiscreteSpace. 

If the space is of type LagrangeDiscreteFunctionSpace it is very simple: 
loop over the entities, 
extract the Lagrange points, 
apply function to the points,
store the result.

Instead, If the space is of type LagrangeDiscontinuousGalerkinSpace instead ,it is not possible to extract the Lagrange points. 
A workaround is to create a fake continuous Lagrange space to extract the points.

I don't like very much this solution and I would prefer to have a consistent way to extract these points.

Is it possible to add the method lagrangePointSet() also to the discontinuous space? 
I tried to look at the code of both spaces but they look pretty different therefore I need a little help and I can try to implement it by myself.

Thank you,
cheers,
Marco.