Changes:
* Bump to 2018.02.11.
* Add man page and bash/fish/zsh completion data.
* Fix/update LICENSE & COPYRIGHT.
* Drop "cmd:ffmpeg" from REQUIRES as ffmpeg is not required but just
recommended. youtube-dl only needs ffmpeg if the user downloads
DASH video+audio contents and wants these to be combined together.
* Add _python and _python3 subpackages.
Contents:
* youtube_dl ships the main youtube-dl monolithic python2.7 script,
as well as the man page and the bash/fish/zsh completion data.
* youtube_dl_python ships the youtube-dl-python python2.7 script.
* youtube_dl_python3 ships the youtube-dl-python3 python3.6 script.
Remarks:
* The base package, youtube_dl, does not depend on any of the python
subpackages.
* The youtube_dl_python and youtube_dl_python3 packages do not depend
on the base package.
* All packages may be installed together.
* Each package works independently of the others.