Blender Git Loki

Fix (unreported): Filebrowser key navigation entry did not change caption correctly

As of this release we're able to navigate with the keyboard in the filebrowsing area. The button caption is changing to an appropriate string whenever a new entry is selected. In @Severins original code a different method was used to determine if a directory was choosen or not, but this got lost while merging the filebrowser rework.

Thanks to @mont29 for review!