Improved logic for ordering a question's answers. Instead of adding the
initial order_by (id_FORUM_DATA_RULES__DEFAULT_ANSWER_SORT_METHOD at
settings/FORUM_DATA_RULES/) as a secondary ordering field regardless of
what the first one is (unless it's the same), choose a tie-breaking
field which is specifically appropriate for each option. This fixes our
shaky case (ordering by most voted when initial order_by is also most
voted), because now the answers are ordered by most voted and then
latest first. In each case, one of the ordering fields is a timestamp,
so there won't be any unbreakable ties.
https://trello.com/c/KRe8tNYZ/494-better-logic-for-ordering-answers