Simple, Reasonable Disengage/Retreat Rule

[Eisenhans]

It's a nice feature to be able to retreat and the supply rule takes care of a lot of arising problems.
Towards the end of the game however, once two sides have both developed quantum reactors, the only thing that counts is speed again. So that propulsion experts should be able to win every game simply by staying alive long enough and then harvesting ripe colonies, while retreating when encountering fleets.