Non ascii strings broken when encoded

```
Base62 encoder breaks non ascii strings (ie french strings with accents)!

To correct it, just add /u unicode modifier into $WORDS regexp, as:

  private static $WORDS    = '/\\b[\\da-zA-Z]\\b|\\w{2,}/u';
```

Original issue reported on code.google.com by `alexand...@monaco.mc` on 5 Mar 2013 at 6:38
