Ship System

a simple ship system that allows you to move units on the water
a custom mover is not included atm but may i'll add it later

you just have to define the water height and your ships and buildings in the init of the system. (example is inside it)

it also includes a waterbuilding sys so you can build them only on water (with custom error etc.)

there are also 2 functions to check if a unit or a location in on water.

Note: uses unit user data slot 20 and 21