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
Merge remote-tracking branch 'upstream/master'
Add RTLnow extractor

Supports http://rtl2now.rtl2.de and http://rtl-now.rtl.de
Add RTLnow extractor
Merge remote-tracking branch 'rzhxeo/rtlnow'
Add VOXnow to RTLnow extractor
Merge pull request #1273 from rzhxeo/rtlnow

Add support for http://voxnow.de
[youtube] Support watch_popup URLs (Fixes #1275)
Merge remote-tracking branch 'upstream/master'
Add YouTube DASH formats to YouTubeIE
fix failed tests
[collegehumor] Allow old-style videos (Fixes #1285)
Cache suitable regular expressions

This speeds up TestAllURLsMatching.test_no_duplicates by about 8000% at the cost of minimal memory overhead.
[generic] Ignore stupid HTTP servers (#1284)
[generic] support HTML5 video
release 2013.08.21