added infantry taking cover behavior

OpenRa.Game/Traits/Helicopter.cs

@@ -48,8 +48,12 @@ namespace OpenRa.Game.Traits
 				Util.TickFacing(ref unit.Facing, desiredFacing,
 					self.Info.ROT);
 
+				var actualSpeed = self.traits.WithInterface<ISpeedModifier>().Aggregate(
+					(float)(self.Info as MobileInfo).Speed,
+					(a, t) => t.GetSpeedModifier() * a);
+
 				// .6f going the wrong way; .8f going sideways, 1f going forward.
-				var rawSpeed = .2f * (self.Info as VehicleInfo).Speed;
+				var rawSpeed = .2f * actualSpeed;
 				var angle = (unit.Facing - desiredFacing) / 128f * Math.PI;
 				var scale = .4f + .6f * (float)Math.Cos(angle);