- stricter timeouts: Instead of adding an entire millisecond, use a list
of timeouts that are supposed to be handled on the same tick. This
reduces the delay between target tick and actual tick, especially for
many timeouts issued to the same tick, i.e. combos.
- consistent timeouts: Timeouts are now guaranteed to be handled in the
order they were issued. Timer rollover is handled properly.
caveat / change to the interface: the returned `timeout_key` is a tuple
of the target timeout tick and the index of the timeout at that tick.