get Order
How "important" this system is. Systems with a higher order value get placed first when assigning keys, meaning the highest order subsystem will get assigned the first key index. If two subsystems have the same order, then it will be picked based on alphabetical order of getDisplayText. This also affects rendering order. There are some static ints in this class for orders that are common. See ORDER_SHIP_UNIQUE and others.
Return
order of the subsystem