Added ability to enable each theme individually.

- Polychromatic themes are enabled by default.
- Other themes need to be enabled individually.
Tweaked settings layout to give more space to the sliders.
Scope matters
Merge branch 'enable-theme' of https://github.com/antons/Polychromatic into antons-enable-theme
Merge branch 'antons-enable-theme' into v1.1-development
Enablement switch sans a label.
Remove global disabling options.