Dictionary Validation

This is also probably not complete. More questions incoming...
Yeh, you should be able to change encodings. This is important, and we can't really regress on this. But it brings into question my previous other statement. We will need a way for users to differentiate between "fail because I will have to fix data with this dictionary change" and "no I really want this change and I promise to add new facts to fix data before I do any extraction". So I change my answer to your original question, and we can fail eagerly and will need a `--force` or what ever you suggested before.