Add support for DCS 2.7 weather generation.

https://github.com/Khopa/dcs_liberation/issues/981

gen/environmentgen.py

@@ -17,6 +17,7 @@ class EnvironmentGenerator:
         self.mission.weather.clouds_thickness = clouds.thickness
         self.mission.weather.clouds_density = clouds.density
         self.mission.weather.clouds_iprecptns = clouds.precipitation
+        self.mission.weather.clouds_preset = clouds.preset
 
     def set_fog(self, fog: Optional[Fog]) -> None:
         if fog is None: