Update ShipMovement.cs

Moved all logic for power consumption out from ShipMovement.cs and into separate components.

More generally why is ship-wide power management done in ShipMovement.cs? This class really has bugger all to do with movement, I'd suggest renaming it to ShipPower.cs

Now that the logic for handling all components is the same, you could implement something like the comment I inserted at the bottom of update.