A description of the various files are in the README

Changelog:

• Add support for SSL client certificate authentication by coletdjnz, dirkf
  • Adds --client-certificate, --client-certificate-key, --client-certificate-password
• Add --match-filter - to interactively ask for each video
• --max-downloads should obey --break-per-input
• Allow use of weaker ciphers with --legacy-server-connect
• Don't imply -s for later stages of -O
• Fix --date today
• Fix --skip-unavailable-fragments
• Fix color in -q -F
• Fix redirect HTTP method handling by coletdjnz
• Improve --clean-infojson
• Remove warning for videos with an empty title
• Run FFmpegFixupM3u8PP for live-streams if needed
• Show name of downloader in verbose log
• [cookies] Allow cookiefile to be a text stream
• [cookies] Report progress when importing cookies
• [downloader/ffmpeg] Specify headers for each URL by elyse0
• [fragment] Do not change chunk-size when --test
• [fragment] Make single thread download work for --live-from-start by Lesmiscore
• [hls] Fix byte_range for EXT-X-MAP fragment by fstirlitz
• [http] Fix retrying on read timeout by coletdjnz
• [ffmpeg] Fix features detection
• [EmbedSubtitle] Enable for more video extensions
• [EmbedThumbnail] Disable thumbnail conversion for mkv by evansp
• [EmbedThumbnail] Do not obey -k
• [EmbedThumbnail] Do not remove id3v1 tags
• [FFmpegMetadata] Remove \0 from metadata
• [FFmpegMetadata] Remove filename from attached info-json
• [FixupM3u8] Obey --hls-prefer-mpegts
• [Sponsorblock] Don't crash when duration is unknown
• [XAttrMetadata] Refactor and document dependencies
• [extractor] Document netrc machines
• [extractor] Update manifest_urls after redirect by elyse0
• [extractor] Update dash manifest_url after redirects by elyse0
• [extractor] Use classmethod/property where possible
• [generic] Refactor _extract_rss
• [utils] is_html: Handle double BOM
• [utils] locked_file: Ignore illegal seek on truncate by jakeogh
• [utils] sanitize_path: Fix when path is empty string
• [utils] write_string: Workaround newline issue in conhost
• [utils] certifi: Make sure the pem file exists
• [utils] Fix WebSocketsWrapper
• [utils] locked_file: Do not give executable bits for newly created files by Lesmiscore
• [utils] YoutubeDLCookieJar: Detect and reject JSON file by Lesmiscore
• [test] Convert warnings into errors and fix some existing warnings by fstirlitz
• [dependencies] Create module with all dependency imports
• [compat] Split into sub-modules by fstirlitz, pukkandan
• [compat] Implement compat.imghdr
• [build] Add make uninstall by MrRawes
• [build] Avoid use of install -D
• [build] Fix Makefile by putnam
• [build] Fix --onedir on macOS
• [build] Add more test-runners
• [cleanup] Deprecate some compat vars by fstirlitz, pukkandan
• [cleanup] Remove unused code paths, extractors, scripts and tests by fstirlitz
• [cleanup] Upgrade syntax (pyupgrade) and sort imports (isort)
• [cleanup, docs, build] Misc fixes
• [BilibiliLive] Add extractor by HE7086, pukkandan
• [Fifa] Add Extractor by Bricio
• [goodgame] Add extractor by nevack
• [gronkh] Add playlist extractors by hatienl0i261299
• [icareus] Add extractor by tpikonen, pukkandan
• [iwara] Add playlist extractors by i6t
• [Likee] Add extractor by hatienl0i261299
• [masters] Add extractor by m4tu4g
• [nebula] Add support for subscriptions by hheimbuerger
• [Podchaser] Add extractors by connercsbn
• [rokfin:search] Add extractor by P-reducible, pukkandan
• [youtube] Add :ytnotifications extractor by krichbanana
• [youtube] Add YoutubeStoriesIE (ytstories:<channel UCID>) by coletdjnz
• [ZingMp3] Add chart and user extractors by hatienl0i261299
• [adn] Update AES key by elyse0
• [adobepass] Allow cookies for authenticating MSO
• [bandcamp] Exclude merch links by Yipten
• [chingari] Fix archiving and tests
• [DRTV] Improve _VALID_URL by vertan
• [facebook] Improve thumbnail extraction by Wikidepia
• [fc2] Stop heatbeating once FFmpeg finishes by Lesmiscore
• [Gofile] Fix extraction and support password-protected links by mehq
• [hotstar, cleanup] Refactor extractors
• [InfoQ] Don't fail on missing audio format by evansp
• [Jamendo] Extract more metadata by evansp
• [kaltura] Update API calls by flashdagger
• [KhanAcademy] Fix extractor by rand-net
• [LCI] Fix extractor by MarwenDallel
• [lrt] Support livestreams by GiedriusS
• [niconico] Set expected_protocol to a public field
• [Niconico] Support 2FA by ekangmonyet
• [Olympics] Fix format extension
• [openrec:movie] Enable fallback for /movie/ URLs
• [PearVideo] Add fallback for formats by hatienl0i261299
• [radiko] Fix extractor by Lesmiscore
• [rai] Add release_year
• [reddit] Prevent infinite loop
• [rokfin] Implement login by P-reducible, pukkandan
• [ruutu] Support hs.fi embeds by tpikonen, pukkandan
• [spotify] Detect iframe embeds by fstirlitz
• [telegram] Fix metadata extraction
• [tmz, cleanup] Update tests by diegorodriguezv
• [toggo] Fix _VALID_URL by ca-za
• [trovo] Update to new API by nyuszika7h
• [TVer] Improve extraction by Lesmiscore
• [twitcasting] Pass headers for each formats by Lesmiscore
• [VideocampusSachsen] Improve extractor by FestplattenSchnitzel
• [vimeo] Fix extractors
• [wat] Fix extraction of multi-language videos and subtitles by elyse0
• [wistia] Fix _VALID_URL by dirkf
• [youtube, cleanup] Minor refactoring by coletdjnz, pukkandan
• [youtube] Added piped instance urls by JordanWeatherby
• [youtube] Deprioritize auto-generated thumbnails
• [youtube] Deprioritize format 22 (often damaged)
• [youtube] Fix episode metadata extraction
• [zee5] Fix extractor by Ashish0804
• [zingmp3, cleanup] Refactor extractors