Operation request: Unicode Normalized Forms

## Summary

It would be a nice addition to support Unicode Normalization Forms:

* NFD
* NFC
* NFKD
* NFKC 

http://www.unicode.org/reports/tr15/

## Exemple 1

### Example Input

lasaña

### Example Output (parameter: NFD)

lasaña

## Exemple 2

### Example Input

Ⅷ

### Example Output (parameter: NFKC)

VIII