After RT-14000 is fixed, we should add some basic Formatter implementations to cover the most common cases.

Some ideas:
* A formatter (or just a StringConverter) that uses toString and valueOf methods (or constructor) - similar to DefaultFormatter in swing.
* A formatter that uses java.text.Format or StringConverter
* Predefined formatters for currency, date, numbers (?) - we have Format instances for that, but can we make it more convenient than that?
* javax.swing.text.MaskFormatter equivalent.
* Regexp formatter or only a filter