Add language identification to apertium-tolk.

It should work like google translate. E.g. if you haven't selected a language, it should try and guess -- and try and guess the "to language" from your locale. If you have selected a language, and the language detection thinks you selected incorretly then it should put up a thing saying "did you mean to translate from X" -- and also, when you click on the language chooser box, then it should highlight somehow the more probable input languages.