allow rail built on water!

if you installed space exploration,rail can also be built in asteroid and platform even space ships,but still cannot built in empty space.

and I rewrite the collision mask for water and space tile,so you now can make entity that can only be place in water or even empty space!
check mod file for more info,any suggestion or imporvment can be provided or even just fork you self because this is published in public domain.

if you are just want vanilla experiance,plz try cargo ships or beautiful_bridge_railway instead