Judges: Shortlist entries

[Julusian]

Currently, no score division is enforced to allow for a reliable shortlist length.
This made the 2017 shortlists be of varying length, as the number of entries had to vary between 4 and 6 entries long.

A config option should be added to configure the length of the shortlist (0 to disable).
And when the judge goes to finalise the scores, they should not be allowed to unless there is a clear divider indicating the top 5 entries.

the following should be allowed, with the split indicated with a |:

19 18 17 17 17 | 15 14 13 12
19 18 17 16 15 | 14 13 12 11

the following should not be allowed, as the | does not sit between scores:

19 18 17 17 16 | 16 15 14 12
19 18 16 15 14 | 14 13 13 12