[Proj] Further help with the swisstopo NTv2 grid shift ?

[Sandro Santilli]

Now that I understood how to use the NTv2 gridshift file provided
by swisstopo (chaining transforms) I'd like to evaluate feasibility
of producing a _new_ NTv2 gridshift file going straight to WGS84
latlong rather than CH1903+ latlong.

How could I proceed to compute the shift ?

--strk;