Function insert

Fleece/Support/SmallVector.hh:139–143

        }

        void insert(iterator where, T item) {
            assert_precondition(begin() <= where && where <= end());
            void *dst = _insert(where, 1, kItemSize);
            *(T*)dst = std::move(item);
        }

        template <class ITER>
        void insert(iterator where, ITER b, ITER e) {