VtuOutputSolver.F90 change DGIndexes

[fgillet]

setting "Discontinuous Galerkin = Logical True" in the vtu output solver change the solution; see e.g. the elmerice test elmerice/Tests/DGsolver/density.sif comment/uncomment the vtu output file.

Tracking what's happening, VtuOutputSolver calls CheckAndCreateDGIndexes in MainUtils; and as I understand this routine overwrite the previously existing DGIndexes (created by CreateDGPerm in MainUtils during initialisation).

DGIndexes in CheckAndCreateDGIndexes should be updated only if not previously existing?
I think this was the intetion with the boolean Failed; but it is never used in the second part of the routine.