note wall time hole test case

DiffractionGratings/grating3D_data_hole.geo

+// note : invcreasing paramaille to 7 leads to:
+// Ndofs 1116912
+// solve wall time mumps  : 634.318s - R00=0.2432916553175037
+// solve wall time pastix : 966.046s - R00=0.2432916553175064
+
 nm  = 1000;
 pp1 = "1Incident Plane Wave";
 pp2 = "2Layers Thicknesses";