The system theme was named Default even though the default theme is Dark.
This addresses that by renaming Default.qss to System.qss. I've made it
backwards compatible so users already using this theme are not affected.
The theme list now shows up as:
-System
-Dark (Default)
-Acri
-Rachni
I have also made it so that you can specify the default theme in the
UI config file.
derrod