[XMinus] Added new extractor.
Merge remote-tracking branch 't0mm0/x-minus'
[README] Adapt code to new style

Next to every IE will download the webpage first anyways.
[README] Mention _og_search_description (#4304)

Lots of sites do have this meta tag, so just add it to the example.
[xminus] Simplify and extend (#4302)