Visualize rough interfaces in Img3D

Random surface generator temporary uses fixed seed.

In the subsequent MRs I need to consider optimization, when the surface is recomputed only when roughness parameter of the corresponding layer is changed.

There should also be separate button in sample builder to update random seed.

Almost finishes #57 (closed)

GUI/View/Realspace/RealspaceBuilder.cpp

@@ -105,7 +105,7 @@ std::unique_ptr<const double2d_t> layerRoughnessMap(const LayerItem& layerItem,
     if (const auto* br = dynamic_cast<const BasicRoughnessItem*>(layerItem.certainRoughness())) {
         auto roughness = LayerRoughness(br->sigma().dVal(), br->hurst().dVal(),
                                         br->lateralCorrelationLength().dVal());
-        int n = 256;
+        int n = sceneGeometry.roughnessResolution;
         double L = 2 * sceneGeometry.layerSize;
         auto rmap = RoughnessMap(n, n, L, L, &roughness, seed); // seed < 0 ==> random every time
         result.reset(new double2d_t(rmap.generateMap()));