- obsolete spaceUntil - it serves no useful purpose
- the old per-model spacing variables are obsolete, as the new approach
requires uniform spacing across all models for new cards
- introduce a new per-deck variable: newSpacing
- don't fill new queue if we've done today's cards
- still need to check cramming / review early
newSpacing is a time in seconds to delay introduction of sibling new cards.
It can be applied as many times as necessary as there is no harm in new cards
being delayed repeatedly. Because the default queue length is 200 and it can
take quite some time for the spaced cards to be placed in the queue again, we
use a separate array to track spaced new cards provided the configured delay
is less than 20 minutes. At times under 20 minutes this number is not a
guaranteed minimum spacing - if the new card queue is empty the spaced cards
will be flushed before checking the new queue again, as otherwise we end up
trying to fill on every repetition. The due counts no longer decrease by more
than one if the spacing is less than the due cutoff, since that confused some
users.
Review cards are now placed at the end of the current review queue, and will
never be rescheduled to a different day. The old approach had a number of
problems:
- the more card models you had, the more likely a card would be spaced
multiple times, resulting in you forgetting the card before you get a chance
to review it
- spacing was applied even if the due card was already late
- repeatedly failing one card over a period of days or weeks would also stave
the other cards of attention
