Support for swapping in a UniquePtrList.

src/Memory/UniquePtrList.hpp

@@ -46,6 +46,11 @@ namespace ArbUt {
             _vector[index] = nullptr;
             return p;
         }
+        void Swap(size_t indexA, size_t indexB){
+            auto temp = _vector[indexA];
+            _vector[indexA] = _vector[indexB];
+            _vector[indexB] = temp;
+        }
         void Set(size_t index, ValueT* ptr) {
             delete _vector[index];
             _vector[index] = ptr;