We want to store the calculated dtstart and dtend in the database so we can
use SQL to fetch records. However, we also need what the user sent us so we
can allow prop-filters to be used as well.
So we store what the user sends us in dtstart_orig and dtend_orig and only
use for relevant prop-filter reports.
From version 10, Postgresql does not allow set-returning functions in
CASE statements. As we're using the functions recursively, we cannot
use LATERAL as suggested in the error message, but we can switch the
condition inside-out with only a limited amount of repetition.
