Add extra fields to toilet codes.

We've received the real data and it has some additional fields we should capture:
- [x] Section (e.g. ``RR``)
- [x] Cluster (within a section, e.g. ``1``, ``2``, ``3``)
- [x] Number (e.g. ``1``, ``2``)
- [x] Type (e.g. ``FT`` (flush toilet), ``TA`` (tap), ``SP`` (stand pipe))