Initial translation system improvements

This is the first set of tweaks to the translation interface. This diff is mostly infrastructural to support later changes (mainly breaking screenshots out of thread stuff) but there are some functional differences in place.

The first is token high-lighting, which isn't required so much with existing tokens, but will be useful as new tokens with less spacing come online.

![Token hilighting](http://jbrt.org/ddg/translation_hilight.png)

The way untranslated tokens are counted has been changed to include tokens with no  valid translations available (see issue #155), so the coverage count for some languages will probably go down with this update.