Non ASCII chars in labels

Hi,
See this error message:

```
Error: Lexical error on line 2. Unrecognized text.
...        id>nom de l’algo]
----------------------^
```

I'd like to use this special apostrophe: `’` instead of this good old one: `'`.
I guess the problem is the same with other chars but I didn't test any.

EDIT: tested with `é` and it works well. Strange.
