[TASK] Allow and replace special characters like umlauts

Currently ``<v:format.uri.sanitizeString />`` strips all special characters like umlauts which is not what one would expect. Open for discussion though is if this feature should be configurable via viewhelper argument.
While you are at it, would you mind adding the Nordic ones as well?

```
`æ` => `ae`,
`ø` => `oe`,
`å` => `aa`
```

Thx ;)