Add ability to select candidate sort order when inputting or confirming results

[jf1]

It can make one's head hurt when the official results list is in a different order than dc's.

dc is currently fixed as 'alpha on first name' (much better than previous unsorted list, so thanks @symroe) but it'd be very useful to be able to change this to 'alpha on second name' for times when official results are presented this way.

If official results are presented in order of most votes then there's no way to pre-sort dc's input fields to match, but these results are easy to check shortly thereafter as the official view is the same as dc's pre-confirm view.

[jf1]

Results officially presented in 'alpha on first name' or 'alpha on last name' order are less easy to confirm, so it'd be beneficial if the /uk_results/posts/-id-/review page enabled resorting.

Perhaps: click Candidates once to sort by first-name, again to sort by last-name, or click Votes (or reload) to return to default sort order.