Docking - get closer and allow target to settle before selecting port

[ElWanderer]

If something odd happens, or if we perform rendezvous manually, we can try to initiate docking from more than 200m away. If the target vessel hasn't been unpacked (or is it loaded?) yet:

• we may have trouble selecting a docking port
• we may find that once within 200m, the target's computer wakes up and steers towards the Sun, throwing out our current alignment and approach.

Docking should probably involve some extra phases:

1. slowly approach to within the unpack/load distance, whichever is smaller
2. pause (kill relative velocity)
3. wait for the target to be available

A posh way of doing step 3 would be with comms - we could send the target a message to ask it if it is ready. That would require developing a comms system first...