A better error dialog.

This is a simple replacement for the JOptionPane showing error messages right now.. on OSX you cannot copy text from a JOptionPane which makes it cumbersome to file error reports.

![skarmavbild 2014-04-01 kl 17 26 35](https://cloud.githubusercontent.com/assets/891566/2580867/4cc31c46-b9b2-11e3-8286-bf5c7248368a.png)