[VnV][telemac3d] Update culvert example with better choices for a few keywords

- NERD for the advection of velocities (as for tracers) rather than
characteristics to decrease differences between sequential and parallel runs
- use of the non-hydrostatic version (but more CPU time consuming)
and conjugate gradient + preconditiong = 34 = 2*17 to solve PPE (more efficient
choice than GMRES here)
- use of preconditioning 34 = 2*17 for the diffusion of tracers + velocities
so that accuracy for the diffusion of tracers can be 1.E-15 without significant
increase of CPU time
- increase of MAXIMUM NUMBER OF ITERATIONS FOR ADVECTION SCHEMES to 100

Update of epsilons (1 order of magnitude less than before for tracers)
Smaller GRAPHIC PRINTOUT PERIOD to draw time series for figure