Create a wider range of status for lang files - fix issue #7

This is not ready, this is a WIP, to get early feedback.

I'll need to update each call to the "critical" API, and probably fix some other things.

So basically, this patch allow to define several tags per page and choose which locale(s) it concern. There are two keywords, 'all' for all locales, 'none' when it's always false. When a tag concern only some locales, we can define an array with the locales instead of the keyword.
What do you think?