Implement ideal group subquestion ordering

[ryooan]

Current behavior

My understanding is group subquestions are currently ordered as follows:

• When open, by highest CP, so if option Y has CP 55% and option X has CP 30%, Y is shown above X.
• This is the case for numeric and dates as well, higher CP medians shown at the top.
• Pending questions seem to have subquestions shown in order created, Luke suggests by subquestion id, which might not be stable.

Expected/desired behavior

Ideal is this:

• Have option to create custom ordering that overrides changes in CP.
• And instead of or in addition to the above it has the following logic:
  • IF all close dates are the same
    • Then sort by highest CP, regardless if binary or continuous
    • Sort by order created when pending
  • IF all close dates are NOT the same:
    • Sort by close date, regardless of value of CP.
    • Sort by close date when pending as well.

We could even potentially get custom ordering for free via the close date sort, as mods and admins could increment each by a few minutes, though this is a bit hacky.

[ryooan]

I'm not seeing a ticket for specifying custom colors for binary group subquestions as well, and am unsure if this should be lumped into this or a separate thing.