Make codes table sortable by columns

[richard-uk1]

It would be handy if one could perform a quick lexographic sort (or numeric in the case of numeric fields) by clicking on a table column header.

It might be that the implementation effort would be too great to justify implementing this I'm not sure.

[rw251]

The data table code is an out of the box solution (https://datatables.net/) so I'm pretty sure that could be turned on very easily.