Extended file dialog (added option to select/unselect files by pattern)

![screen shot 2014-08-06 at 09 18 29](https://cloud.githubusercontent.com/assets/7167030/3823597/9fd094da-1d3b-11e4-9dae-6cedf9efa50a.png)

Patch has originally been written by Ronny Binder <rbi@hinderlingvolkart.com>