Adds supranational areas to pygal

available areas are defined in the i18n file
it can be used like this:
    - add("Legend", "europe")
    - add("Legend", ["europe", "oecd"])
    - or even add("Legend", {"nafta", 1000}) if you wish to add a value for the
    entire area
Fixes supranational code leaving ghost generic
Merge branch 'master' of ssh+git://github.com/cristen/pygal

Conflicts:
	pygal/i18n.py