Youtube-transcript-api

Fixes:

- Timestamp formatting in `WebVTTFormatter` has been fixed
- When requests to YouTube return an error status code, a `YouTubeRequestFailed` exception is raised, wrapping the status code and error message

Fixes:

As of lately YouTube will occasionally return a page which requires the user to give consent to cookies being saved. Whenever this page was returned this this module was not able to process the response. Now it is able to recognise this case and create a consent cookie if needed.

Features:

* Added support for different formatters, including support for WebVVT (thanks crhowell!)
* Added distinct error message which appears when running into rate limits (thanks kovan)

Fixes:

* CLI now also supports video IDs starting with a dash (thanks crhowell)
* Documentation improvements (thanks dafiulh)

Changes:

- Typos in Documentation fixed.

Changes:
- added support for using cookies, to be able to retrieve age restricted videos
- API usage: `YouTubeTranscriptApi.get_transcript(video_id, cookies='/path/to/your/cookies.txt')`
- CLI usage: `youtube_transcript_api <first_video_id> <second_video_id> --cookies /path/to/your/cookies.txt
`

Thanks to danielcliu for the contribution!

Changes:

- fixed a bug in the CLI where no videos could be retrieved if no language was specified