[core] Decode environment variables with filesystem encoding (Fixes #3854, Fixes #3217, Fixes #2918)

Introduces compat versions of os.getenv and os.path.expanduser
[utils] Add posix expanduser implementation and clarify the original source
[glide] Add new extractor

Added an extractor for glide.me shared messages.  Glide is a movile video messaging services.  You can share the link to the messages easily enough and this would allow you to download and save the actual video.
added "bild.de" as extractor
[cnn] Fix for urls ending in '.cnn-ap' (fixes #3985)
Added extractor for crunchyroll 'playlists' i.e. series. so that one can, e.g. download all episodes of a series
[arte.tv:+7] Use original format ids to avoid duplicates
Forgot to reverse extracted video urls so they are in correct order for video selection args
[arte.tv:+7] Improve title extraction (Closes #3995)
[arte.tv] Remove unused import
[francetv] Force m3u8 formats extension to mp4 (Closes #3997)
[youtube] Only set language when necessary

We only need to set the language when we are using a login; otherwise it will always be English.
[pbs] Add support for tabbed frontline videos (Closes #4006)
[cinemassacre] Fix extraction (Closes #4008)
[thoughtworks] wistia support added
[francetv] Lower preference of direct links (Closes #4010, closes #3947)

Direct links fail with 403, fallback on f4m for now until further investigations.
[thoughtworks] wistia regex modified
Merge pull request #4009 from Dineshs91/thoughtworks

[thoughtworks] wistia support added
[generic/wistia] Improve regex
[funnyordie] Fix extraction (Closes #4011)