[UGGrid] Use std::size_t as loop counter

This fixes a few signed/unsigned warnings

dune/grid/uggrid/uggridintersections.cc

@@ -111,7 +111,7 @@ UGGridLevelIntersection<GridImp>::geometryInInside () const
     auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
     GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-    for (int i=0; i<coordinates.size(); i++) {
+    for (std::size_t i=0; i<coordinates.size(); i++) {
 
       // get number of corner in UG's numbering system
       int ugIdx     = UGGridRenumberer<dim-1>::verticesDUNEtoUG(i, intersectionGeometryType);
@@ -140,7 +140,7 @@ UGGridLevelIntersection<GridImp>::geometry () const
     auto coordinates = GeometryImpl::makeCornerStorage(numCornersOfSide);
     GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-    for (int i=0; i<coordinates.size(); i++) {
+    for (std::size_t i=0; i<coordinates.size(); i++) {
 
       int ugIdx     = UGGridRenumberer<dim-1>::verticesDUNEtoUG(i, intersectionGeometryType);
       int cornerIdx = UG_NS<dim>::Corner_Of_Side(center_, neighborCount_, ugIdx);
@@ -179,7 +179,7 @@ UGGridLevelIntersection<GridImp>::geometryInOutside () const
     auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
     GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-    for (int i=0; i<coordinates.size(); i++) {
+    for (std::size_t i=0; i<coordinates.size(); i++) {
 
       // get the node in this element
       int localCornerNumber = UG_NS<dim>::Corner_Of_Side(center_, neighborCount_, i);
@@ -268,7 +268,7 @@ UGGridLeafIntersection< GridImp >::geometryInInside () const
       auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++)
+      for (std::size_t i=0; i<coordinates.size(); i++)
       {
         // get number of corner in UG's numbering system
         int cornerIdx = UG_NS<dim>::Corner_Of_Side(center_, neighborCount_, i);
@@ -286,7 +286,7 @@ UGGridLeafIntersection< GridImp >::geometryInInside () const
       auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++) {
+      for (std::size_t i=0; i<coordinates.size(); i++) {
 
         // Get world coordinate of other element's vertex
         const FieldVector<UGCtype,dimworld>& worldPos = UG_NS<dim>::Corner(otherFace->first,
@@ -337,7 +337,7 @@ UGGridLeafIntersection< GridImp >::geometry () const
       auto coordinates = GeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++) {
+      for (std::size_t i=0; i<coordinates.size(); i++) {
 
         int cornerIdx = UG_NS<dim>::Corner_Of_Side(center_, neighborCount_, i);
         const typename UG_NS<dim>::Node* node = UG_NS<dim>::Corner(center_, cornerIdx);
@@ -356,7 +356,7 @@ UGGridLeafIntersection< GridImp >::geometry () const
       auto coordinates = GeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++) {
+      for (std::size_t i=0; i<coordinates.size(); i++) {
 
         // get number of corner in UG's numbering system
         int cornerIdx = UG_NS<dim>::Corner_Of_Side(otherFace->first, otherFace->second, i);
@@ -402,7 +402,7 @@ UGGridLeafIntersection< GridImp >::geometryInOutside () const
       auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++) {
+      for (std::size_t i=0; i<coordinates.size(); i++) {
 
         // get number of corner in UG's numbering system
         int cornerIdx = UG_NS<dim>::Corner_Of_Side(center_, neighborCount_, i);
@@ -431,7 +431,7 @@ UGGridLeafIntersection< GridImp >::geometryInOutside () const
       auto coordinates = LocalGeometryImpl::makeCornerStorage(numCornersOfSide);
       GeometryType intersectionGeometryType = (numCornersOfSide == 4 ? GeometryTypes::cube(dim-1) : GeometryTypes::simplex(dim-1));
 
-      for (int i=0; i<coordinates.size(); i++) {
+      for (std::size_t i=0; i<coordinates.size(); i++) {
 
         // get the local coordinate of j-th corner
         int v = UG_NS<dim>::Corner_Of_Side(otherFace->first,otherFace->second,i);