[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
[ard] Add rss support
Added extractor for crunchyroll 'playlists' i.e. series. so that one can, e.g. download all episodes of a series
Forgot to reverse extracted video urls so they are in correct order for video selection args
[ard] make rss match more universal
[BelgianNational] New extractor added
[BelgianNational] corrected indentation
[vrt] Improve extractor
Merge branch 'Dineshs91-belgiannational-ie'
Set '--simulate' if any of the printing options is given (fixes #3036)

That's what the help messages say.
Previously it would only set '--skip-download', which would write thumbnail,
descriptions or subtitles if they were requested (for example you may have set
'--write-thumbnail' in the config file).
Merge branch 'compat-getenv-and-expanduser' of https://github.com/dstftw/youtube-dl into dstftw-compat-getenv-and-expanduser

Conflicts:
	test/test_utils.py
	youtube_dl/__init__.py
Merge branch 'dstftw-compat-getenv-and-expanduser'
[generic] Allow new SWFObject()-style imports

This embed style is used on http://www.bitburger-open.de/ , but that is not included as a test case since the format is likely to be temporary.
[YoutubeDL] Output avconv/ffmpeg versions if -v is given
[ffmpeg] Warn if ffmpeg/avconv version is too old (Fixes #4026)
[generic] Handle audio streams that do not implement HEAD (Fixes #4032)
Merge remote-tracking branch 'gabeos/crunchyroll-show-playlist'
[crunchyroll:playlist] Simplify (#3988)
Credit @gabeos for crunchyroll:playlist (#3988)