This release switches from using `requests` to `httpx` for making http requests,
and from threads to `asyncio` for concurrency. This enables easier
implementation of new features, but has no breaking changes for the CLI.
* **BREAKING**: Require Python 3.7 or later.
* Add `--rate-limit` option to `download` for limiting maximum bandwidth when
downloading.
* Add `--compact` option to `download` for displaying one video per line.
* Allow passing multiple video ids to `download` to download multiple videos
successively.
* Improved progress meter, updates on each chunk downloaded, instead of each VOD
downloaded.
* Improved speed estimate, displays recent speed instead of average speed since
the start of download.
* Decreased default concurrent downloads to 5. This seems to be enough to
saturate the download link in most cases. You can override this by setting the
`-w` option. Please test and report back if this works for you.