[downloader/(common/http)] Changes calculation of the rate-limit. (Fix #2297, fix #2140, fix #595, fix #2370)
 [downloader/common] Fix possible negative sleep time in slow_down()
[common] Split _download_json
Add ability for extractor to use _parse_json
[howstuffworks] Rewrite extractor
[howstuffworks] Update extractor
Fix utils.py for PyPy on Windows

The line
```python
from __future__ import unicode_literals
```
introduced in commit [ecc0c5ee01f0e5bdd6af0c32cb5b4adcb2a2f78c](https://github.com/rg3/youtube-dl/commit/ecc0c5ee01f0e5bdd6af0c32cb5b4adcb2a2f78c) broke youtube-dl for PyPy on Windows, making it unable to locate WinAPI functions.
Error: "TypeError: function name must be a string or integer"

Adding "b" prefix to strings with WinAPI function names fixes it.
[radio.de] Add support for radio.de websites (Closes #4393)
[prosiebensat1] Add support for playlists (fixes #4357)
[prosiebensat1] Fix broken tests
[extractor/common] Add description to playlist_result
[prosiebensat1] Improve and simplify
Merge branch 'akretz-master'
Credit @akretz for prosiebensat1 playlist support (#4394)
Handle --get-url with merged formats (fixes #2883)

Outputs one URL per line
[nhl] Make sure we add '_sd' before the extension (fixes #4397)

'.replace' would find the first dot in the path.
add direct screenwavemedia.com URL support
add teamfourstar.com support
[tvigle] Update test and modernize
[bliptv] Add support for audio-only files (Fixes #4404)
Merge branch 'master' of github.com:rg3/youtube-dl