Why the nuke is always minimal effect

Created by: Sprok0

https://github.com/d3athrow/vgstation13/blob/Bleeding-Edge/code/game/gamemodes/nuclear/nuclearbomb.dm at line 298, it checks if the nuke was close enough to the center of the z-level to count as on-board, but it wasn't updated when maps were made 500x500. If you detonate the nuke at the south-west syndie shuttle dock, it counts as on-station.