[arte+7] Improve title extraction

[dstftw]

22:44:44 < qwebirc83161> Hello everyone
22:45:37 < qwebirc83161> I don't have a github account and found no contact email address (probably for good reason), so I thought I'd try here.
22:46:25 < qwebirc83161> I'd wish to propose a change on https://github.com/rg3/youtube-dl/blob/master/youtube_dl/extractor/arte.py#L96 - maybe it would be possible to add "player_info['VSU'] as well.
22:47:03 < qwebirc83161> The problem is that ARTE+7 has multi-episode series. E.g. "Philosophie": http://www.arte.tv/guide/de/053445-005/philosophie
22:47:37 < qwebirc83161> The Subtitle (See JSON: http://arte.tv/papi/tvguide/videos/stream/player/D/053445-005_PLUS7-D/ALL/ALL.json "VSU":"Scham") is different for each episode, but the title is identical.
22:48:28 < qwebirc83161> This means that running "youtube-dl -t" will just create a "Philosophie" title each time, instead of e.g. "Philosophie - Scham", which woud be player_info['VTI'] + " - " + player_info['VSU'] in https://github.com/rg3/youtube-dl/blob/master/youtube_dl/extractor/arte.py#L96
22:48:46 < qwebirc83161> I hope someone reads this and feels inspired! :)