Refactor Settings

[CryZe]

At the moment the settings are entirely described through the enum variants and their values. However this has become quite annoying because we use different variants for the different kinds of combo boxes we have. It would be much better if we could just dynamically describe a combo box instead. This is not currently possible because the options would need to be part of the value, which means they would also be stored back when changing such a setting, which doesn't make any sense.

We should look into further improvements such as groups and tooltips while doing this refactoring.