have all test case scaling nm=1

DiffractionGratings/grating3D_data_U.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_bi_sinusoidal.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_checker.geo

-nm  = 10000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_convergence.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_hole.geo

@@ -2,9 +2,9 @@
 // Ndofs 1116912
 // solve wall time mumps  : 634.318s - R00=0.2432916553175037
 // solve wall time pastix : 966.046s - R00=0.2432916553175064
-// beware : very near a Rayleigh anomaly
+// beware : very close to a Rayleigh anomaly
 
-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_nanowire_solarcell.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_pyramid.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_retrieve_2D_lamellar.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";

DiffractionGratings/grating3D_data_skewed_lattice.geo

-nm  = 1000;
+nm  = 1;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";
 pp3 = "3Scatterer Properties";