Don't use at() instead [] when length is checked/known

apps/openmw/mwrender/objectpaging.cpp

@@ -417,7 +417,7 @@ namespace MWRender
                 {
                     try
                     {
-                        unsigned int index = cell->mContextList.at(i).index;
+                        unsigned int index = cell->mContextList[i].index;
                         if (esm.size()<=index)
                             esm.resize(index+1);
                         cell->restore(esm[index], i);

apps/openmw/mwworld/cellstore.cpp

@@ -547,7 +547,7 @@ namespace MWWorld
             try
             {
                 // Reopen the ESM reader and seek to the right position.
-                int index = mCell->mContextList.at(i).index;
+                int index = mCell->mContextList[i].index;
                 mCell->restore (esm[index], i);
 
                 ESM::CellRef ref;
@@ -605,7 +605,7 @@ namespace MWWorld
             try
             {
                 // Reopen the ESM reader and seek to the right position.
-                int index = mCell->mContextList.at(i).index;
+                int index = mCell->mContextList[i].index;
                 mCell->restore (esm[index], i);
 
                 ESM::CellRef ref;

apps/openmw/mwworld/store.cpp

@@ -1003,7 +1003,7 @@ namespace MWWorld
         if (index >= mStatic.size()) {
             return nullptr;
         }
-        return &mStatic.at(index);
+        return &mStatic[index];
     }
 
     const ESM::Attribute *Store<ESM::Attribute>::find(size_t index) const