quick fix for fronda - just populate article list and get the first page of article content
Update National Geographic. Fixes #1315373 [calibre National Geographic News recipe is not fetching news anymore since few week ago](https://bugs.launchpad.net/calibre/+bug/1315373)
drop too old articles
remove fronda, as its new pages are impossible to parse

The first (solveable but resulting in monstrous overhead) problem is that articles don't have dates in feed nor category pages,
The second (not solvable for me) is multipage articles link to next page using relative links.
remove fornda's icon
pep8
Merge branch 'master' of https://github.com/t3d/calibre