Performance fixes

First of all I'd like to appreciate great work you did on Videodevil (hopefully it will be merged soon) :thumbsup:

Here is a patch that greatly improves performance of video list processing. Especially on slow devices (on my RPi list of videos for certain site took about 30s, after patch it was about 6s).

The biggest problem was in _clean1()_ and _decode()_. They in fact do the same thing and both were suboptimal.
I have also rearranged couple of things and removed unnecessary tables. I believe it should produce the same result as original code.