Save file optimizations/map generation limiter

[Mylon]

Can we limit map generation to keep save files smaller? I recall a defining feature of 0.15 was faster map generation, which means there's no longer a reason to chart twice the distance out from radar scan range just in case the player goes there.

Additionally, if there was a way to not send 'pristine' chunks to players in multiplayer and force them to generate them as part of the catchup process, that could also help with hosting large maps.