Twitch-dl

* Fix more compat issues Python < 3.10 (152)

* Fix compat with Python < 3.10 (152)
* Fix division by zero in progress calculation when video duration is reported
as 0

* **Requires Python 3.8+**
* Migrated to Click library for generating the commandline interface
* Add shell auto completion, see 'Shell completion' in docs.
* Add setting defaults via environment variables, see 'Environment variables' in
docs
* Add `download --concat` option to avoid using ffmeg for joinig vods and concat
them instead. This will produce a `.ts` file by default.
* Add `download --dry-run` option to skip actual download (thanks metacoma)
* Add video description to metadata (129)
* Add `clips --compact` option for listing clips in one-per-line mode

* Fix error caused by twitch requiring https for the usher api (thanks
deanpcmad)

* Replace client ID with one that works for now (thanks mwhite34)

* Fix error caused by twitch changing the Usher domain (thanks adsa95)