Add always backlight feature

Ohai!

I took the liberty of adding a new feature to this project. Backlight now supports always backlighting even if you have a selection. I did not want to impose a new default behavior so I added it as a new configuration options.
I felt that having three menu items laying around in the Edit menu was a bit overkill so I refactored the menu item code and made it into it's own submenu.

It also contains a new screenshot.. and yeah, I rewrote some other stuff. Hope you like it!

![screenshot](https://cloud.githubusercontent.com/assets/57446/4816276/3e22f432-5ede-11e4-8548-6c710e8b4eb5.png)