Convert to new unit APIs, remove old APIs.

There are probably plenty of raw ints around that never used the old
conversion APIs, but we'll just need to fix those when we see them.

Fixes https://github.com/Khopa/dcs_liberation/issues/558

game/weather.py

@@ -10,6 +10,7 @@ from typing import Optional, TYPE_CHECKING
 from dcs.weather import Weather as PydcsWeather, Wind
 
 from game.settings import Settings
+from game.utils import Distance, meters
 
 if TYPE_CHECKING:
     from game.theater import ConflictTheater
@@ -39,7 +40,7 @@ class Clouds:
 
 @dataclass(frozen=True)
 class Fog:
-    visibility: int
+    visibility: Distance
     thickness: int
 
 
@@ -56,7 +57,7 @@ class Weather:
         if random.randrange(5) != 0:
             return None
         return Fog(
-            visibility=random.randint(2500, 5000),
+            visibility=meters(random.randint(2500, 5000)),
             thickness=random.randint(100, 500)
         )