YoutubeDL: only set the ‘formats’ field of the info_dict if it was already set before

It caused a circular reference error, when trying to dump it to json (for example with the test video for myvideo.de or any other video without formats)
YoutubeDL: rename `_fd_progress_hooks` back to `_progress_hooks`

In the future it may report more things.
[subtitles-tests] Fix youtube test

It returns now a single info_dict
[YoutubeDL] fix tests (Closes #2036)
Merge remote-tracking branch 'origin/master'
[bliptv] Remove support for direct downloads

This is now handled by the generic IE
[myvideo] Use RTMP instead of RTMPT (Fixes #2032)
[mplayer] Fix error introduced by downloader separation
Remove dead code
Add a resolution field and improve general --list-formats output
Add temporary _sort_formats helper function
Add more tests for format selection
[youtube] Simplify format specification
[dreisat] Use centralized format sorting
[mit] Add support for multiple formats
[spiegel] Use centralized sorting
[zdf] Use centralized sorting
[mdr] Use centralized format selection
[imdb] Extractor for lists (#2033)
[imdb] Add playlist test