2.x:

- improve tree [DONE]
- install icon system-wide [DONE]
- update configure/Makefile [DONE]
- about dialog [-> 3.x]
- rename widgets [DONE]
- merge splashy-tc [-> 3.1]

3.x:

- internal rework [DONE]
- new ui [?? need input]
- about dialog []
- merge splashy-tc [DONE (as SplashyManager)]
- improve config-file handling []
- possiblity to remove themes []
- make removed themes disappear from comboboxes []

4.x:

- rewrite core []
- possibilty to edit themes []
