Steering manager becomes disassociated

[hvacengi]

Originally reported here: https://www.reddit.com/r/Kos/comments/3vk2tz/splitting_a_ship_in_two_kos_cores_controlling/

When staging with multiple probe cores, the steering manager some times looses it's proper control reference. This has something to do with how the cpu vessel is assigned/updated and which vessel is the "dominant" vessel and retains the original underlying ID value.

I have already started working on a fix for this, and will focus on it significantly more after we release 0.19.0.