* Make drunkins_enqueue_items() support a new...

* Make drunkins_enqueue_items() support a new 'can_override_fetch=pass_through_start(_by_default)' capability / proper logging after queueing the items  / enqueue_by_fetcher. The capabilities are not fit for use yet, though (see lots of @todos about locking).
* Squash bugs in drunkins_enqueue_items().
* Change 'skip_last_marker' runner setting to 'add_last_marker', which is clearer - now that we decided to make it have different default in different functions.