Create extract_info method
Add a method for extracting info from a list of urls
Merge branch 'master' into extract_info_rewrite
Use extract_info in YoutubePlaylist and YoutubeSearch
Use extract_info in BlipTV User and Youtube Channel
`extract_info` now expects `ie.extract` to return a list in the format proposed in issue 608.

Each element should have a '_type' key specifying if it's a video, an url or a playlist.
`extract_info` will process each element to get the full info
Add auxiliary methods to InfoExtractor to set the '_type' key and use them for some playlist IEs
When a redirect is found return the new url using the new style
Merge branch 'master' into extract_info_rewrite
Add title and id to playlist results

Not all IE give both. They are not used yet.
Pass the playlist info_dict to process_info

the playlist value can be used in the output template
Merge branch 'master' into extract_info_rewrite
Add progress counter for playlists

Closes #276
Change the order for extracting/downloading

Now it gets a video info and directly downloads it, the it pass to the next video founded.
In MetacafeIE return a url if YoutubeIE should do the job
Implement the playlist/start options in FileDownloader

It makes it available for all the InfoExtractors
Add a playlist_index key to the info_dict, can be used in the output template
Merge branch 'extract_info_rewrite'