WIP: Fixing text padding

The width of the text node does not compensate correctly for padding.

#### Example Code

```javascript
var str = 'hmmmmmmmmmmm';
var txt = new lively.morphic.Text(lively.rect(20,10,60,50), str);
txt.openInWorld();
txt.focus();
txt.setPadding(lively.Rectangle.inset(5, 10));
```

#### Result

![paddingbug](https://f.cloud.github.com/assets/479238/187103/cf7b467c-7d45-11e2-82b1-6f90d8715b0e.png)