Aircraft Takeoff & Landing Sounds (Fixed-Wing)

Added Takeoff & Landing sounds to planes.

Changed Aircraft Trait, TakeoffSounds & LandingSounds are now arrays & accept a list of sound files & it will randomly select one to play.

Changed/fixed take off & landing sounds to originate from the aircraft location, rather than play a global sound.

OpenRA.Mods.Common/Activities/Air/Land.cs

@@ -20,6 +20,8 @@ namespace OpenRA.Mods.Common.Activities
 		readonly Target target;
 		readonly Aircraft aircraft;
 
+		bool soundPlayed;
+
 		public Land(Actor self, Target t)
 		{
 			target = t;
@@ -34,6 +36,12 @@ namespace OpenRA.Mods.Common.Activities
 			if (IsCanceled)
 				return NextActivity;
 
+			if (!soundPlayed && aircraft.Info.LandingSounds.Length > 0 && !self.IsAtGroundLevel())
+			{
+				Game.Sound.Play(SoundType.World, aircraft.Info.LandingSounds.Random(self.World.SharedRandom), aircraft.CenterPosition);
+				soundPlayed = true;
+			}
+
 			var d = target.CenterPosition - self.CenterPosition;
 
 			// The next move would overshoot, so just set the final position