Incompatibility of 3D IO mesh with new Nek version

I noticed that when running an inflow-outflow simulation using the generated 3D mesh (`base.rea`), the simulation blows up. This doesn't happen if the 3D mesh is obtained extruding `base2d.rea` with `n2to3`. From a first investigation it might be due to what is written in the line `O` of the boundary conditions in the `.rea` and to an update in the call of the routine `BCNEUTR`.