Icon set for GUI

[jochenklein]

We need a simple and free icon set to extend or replace the text of simple functions in the UI, like "new", "delete", "import", "export" and so on. Some suggestions:

• Bootstrap Glyphicons: http://getbootstrap.com/components/#glyphicons
• Font Awesome: http://fortawesome.github.io/Font-Awesome/icons/
• Ionicons: http://ionicons.com/

@KaiSta, what do you think?