reduce ai population limit for using systems
replace slow rangemaps with an actually slow version

which also has some more differences between short/medium/long range,
depending on techlevel
factor GetMaxHabitants() functionality of CSector
guarantee all spaceflight minors a minimum maximum population of 30k

This is currently needed for the most restrictive type 2 shipyard.
I hope none ever changes this in buildings editor. Unhardcoding would
require iterating over all buildings which is costly.
There are a few minors with size 3 ships, but those have their own
type 3 shipyard (and they will have 30k+ now too).
replace medium range with a version slightly slower than classic

instead of slightly faster, so that it matches the small map, basically