Validate remaining language codes

- `art-loglan` and `art-guaspi` are missing an `x-' after the hyphen
- `en-bpfk`'s `bpfk` is four letters long and therefore treated as a script `Bpfk`, but no script with that code exists; to fix, add a letter somewhere
- `fr-facile`: change to `fr-simple` I guess
- `test`: turns out `x-test` is valid by itself