- Move SegmentedStreamWorker.wait to AwaitableMixin
- Make both SegmentedStream{Worker,Writer} inherit from AwaitableMixin

- Refactor DASHStreamWorker.iter_segments()
- Replace dash_manifest.sleeper() with SegmentedStreamWorker.wait(),
  and make the worker thread shut down immediately on close().
- Prevent unnecessary wait times for static manifest types by calling
  close() after all segments were put into the writer's queue.

- Replace dash_manifest.sleep_until() with SegmentedStreamWriter.wait(),
  and make the thread-pool threads shut down immediately on close().
- Fix segment name logging

- Move SegmentedStreamWorker.wait to AwaitableMixin
- Make both SegmentedStream{Worker,Writer} inherit from AwaitableMixin

…#4630)
- Refactor DASHStreamWorker.iter_segments()
- Replace dash_manifest.sleeper() with SegmentedStreamWorker.wait(),
  and make the worker thread shut down immediately on close().
- Prevent unnecessary wait times for static manifest types by calling
  close() after all segments were put into the writer's queue.

- Replace dash_manifest.sleep_until() with SegmentedStreamWriter.wait(),
  and make the thread-pool threads shut down immediately on close().
- Fix segment name logging