Function used in mission creation.
Represents a disc in wich entities can be teleported.
Entities are teleported on a random point within the zone.
name : name of the zone. 2 ZONES CANNOT SHARE THE SAME NAME.
radius : radius of the delimiting circle in meter
use_z : if checked, the z property will be used
z : z cords of the disc
Angle : heading of entities after teleportation