Move IsMovingVertically to IMove

- avoids an Aircraft trait look-up in #11886
- potentially useful for future additional locomotors (jumpjet), custom locomotors in external mods, possibly future updates to default ground locomotor (Mobile) with regard to behavior on slopes

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -308,6 +308,7 @@ namespace OpenRA.Traits
 		Activity VisualMove(Actor self, WPos fromPos, WPos toPos);
 		CPos NearestMoveableCell(CPos target);
 		bool IsMoving { get; set; }
+		bool IsMovingVertically { get; set; }
 		bool CanEnterTargetNow(Actor self, Target target);
 	}
 

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -115,13 +115,13 @@ namespace OpenRA.Mods.Common.Traits
 		public int TurnSpeed { get { return Info.TurnSpeed; } }
 		public Actor ReservedActor { get; private set; }
 		public bool MayYieldReservation { get; private set; }
-		public bool IsMovingVertically { get; private set; }
 
 		bool airborne;
 		bool cruising;
 		bool firstTick = true;
 
 		bool isMoving;
+		bool isMovingVertically;
 		WPos cachedPosition;
 
 		public Aircraft(ActorInitializer init, AircraftInfo info)
@@ -182,7 +182,7 @@ namespace OpenRA.Mods.Common.Traits
 			var oldCachedPosition = cachedPosition;
 			cachedPosition = self.CenterPosition;
 			isMoving = (oldCachedPosition - cachedPosition).HorizontalLengthSquared != 0;
-			IsMovingVertically = (oldCachedPosition - cachedPosition).VerticalLengthSquared != 0;
+			isMovingVertically = (oldCachedPosition - cachedPosition).VerticalLengthSquared != 0;
 
 			Repulse();
 		}
@@ -495,6 +495,8 @@ namespace OpenRA.Mods.Common.Traits
 
 		public bool IsMoving { get { return isMoving; } set { } }
 
+		public bool IsMovingVertically { get { return isMovingVertically; } set { } }
+
 		public bool CanEnterTargetNow(Actor self, Target target)
 		{
 			if (target.Positions.Any(p => self.World.ActorMap.GetActorsAt(self.World.Map.CellContaining(p)).Any(a => a != self && a != target.Actor)))

OpenRA.Mods.Common/Traits/Mobile.cs

@@ -327,6 +327,7 @@ namespace OpenRA.Mods.Common.Traits
 		readonly Actor self;
 		readonly Lazy<IEnumerable<int>> speedModifiers;
 		public bool IsMoving { get; set; }
+		public bool IsMovingVertically { get { return false; } set { } }
 
 		int facing;
 		CPos fromCell, toCell;