Fix weather particle physics.

The trait documentation specified that the speed
and offset values are px/tick, but they have actually
always been treated as px/render.

Fix the update logic and rescale the map definitions
to account for the fixed behaviour.

mods/cnc/maps/gdi06/rules.yaml

@@ -6,12 +6,10 @@ World:
 		StartingMusic: rain
 	WeatherOverlay:
 		ChangingWindLevel: true
-		WindLevels: -5, -3, -2, 0, 2, 3, 5
-		WindTick: 150, 550
 		InstantWindChanges: false
 		UseSquares: false
 		ScatterDirection: 0, 0
-		Gravity: 8.00, 12.00
+		Gravity: 15, 25
 		SwingOffset: 0, 0
 		SwingSpeed: 0, 0
 		SwingAmplitude: 0, 0