Give a container move operations

Reason

Containers tend to get large; without a move constructor and a copy constructor an object can be expensive to move around, thus tempting people to pass pointers to it around and getting into resource management problems.

Example

Sorted_vector<int> read_sorted(istream& is)
{
    vector<int> v;
    cin >> v;   // assume we have a read operation for vectors
    Sorted_vector<int> sv = v;  // sorts
    return sv;
}

A user can reasonably assume that returning a standard-like container is cheap.

Enforcement

???