FEM: modernize C++: use range-based for loop

src/Mod/Fem/Gui/ViewProviderFemConstraintSpring.cpp

@@ -128,8 +128,8 @@ void ViewProviderFemConstraintSpring::updateData(const App::Property* prop)
         Gui::coinRemoveAllChildren(pShapeSep);
 #endif
 
-        for (std::vector<Base::Vector3d>::const_iterator p = points.begin(); p != points.end(); p++) {
-            SbVec3f base(p->x, p->y, p->z);
+        for (const auto & point : points) {
+            SbVec3f base(point.x, point.y, point.z);
             SbVec3f dir(n->x, n->y, n->z);
             SbRotation rot(SbVec3f(0, -1.0, 0), dir);
 #ifdef USE_MULTIPLE_COPY