Save subtitles using the same code for all the options
Use a dictionary for storing the subtitles

The errors while getting the subtitles are reported as warnings, if no subtitles are found return and empty dict.
YoutubeIE: use the same function for getting the subtitles for the "--write-sub" and "--all-sub" options
YoutubeIE: don't crash when trying to get automatic captions if the videos has standard subtitles.
Don't try to write the subtitles if it's None
[youtube] add algo for length 80 and update player info
Merge pull request #937 from jaimeMF/subtitles_rework

Subtitles rework
[youtube] Fix download of subtitles with '--all-subs'

If _extract_subtitles is called the option 'write subtitles' is always true.
Add a post processor for embedding subtitles in mp4 videos (closes #1052)
XHamsterIE: Fix video extension

Cut off GET parameter
XHamsterIE: Add video description
Merge pull request #1301 from rzhxeo/xhamster

XHamsterIE: Fix video extension and add video description
[xhamster] use determine_ext
Print a message before embedding the subtitles
Allow to specify multiple subtitles languages separated by commas (closes #518)
[youtube] update algo for length 86 (fixes #1302)
release 2013.08.23
Switch to domain yt-dl.org
[youtube] update algo for length 84