New icon for Turret Control Panels

It also now has a depowered state. (Not pictured)

I also organized the file a bit because it was all over the place.

So don't skewer me for code I didn't touch please.

I just changed update_icon(), and power_change(), and New()
Merge pull request #4678 from Ikarrus/turretcontrolicon

New icon for Turret Control Panels