Case expressions must be orderable

[atombender]

Is your feature request related to a problem? Please describe.
It should be possible to express queries like:

SELECT * FROM articles
ORDER BY CASE
  WHEN published THEN published_at
  ELSE timestamptz '1900-01-01'
END

However, CaseExpression is not orderable, so you can't do:

q.Order(goqu.Case(...).Asc())

Describe the solution you'd like
Case() should return an orderable expression.

[doug-martin]

@atombender thank you for your feature request! This has been released under v9.16.0

[atombender]

Awesome, thanks!