[nuevo] Generalize nuevo extractor and add support for trollvids

Supports only the nuevo player for now (most common).

[trollvids] convert duration to an int

[trollvids] added a test

[trollvids] made flake8 shut up

Generalized the Nuevo extractor

Affects: anitube, trollvids, trutube

[nuevo] Complied with the code comments.

youtube_dl/extractor/__init__.py

@@ -726,6 +726,7 @@ from .toutv import TouTvIE
 from .toypics import ToypicsUserIE, ToypicsIE
 from .traileraddict import TrailerAddictIE
 from .trilulilu import TriluliluIE
+from .trollvids import TrollvidsIE
 from .trutube import TruTubeIE
 from .tube8 import Tube8IE
 from .tubitv import TubiTvIE