Split Locomotor trait from Mobile

Add GrantConditionOn*Layer traits

This allows to
- drop some booleans from Locomotor
- drop a good part of the subterranean- and jumpjet-specific code/hacks from Mobile
- grant more than 1 condition per layer type (via multiple traits)
- easily add more traits of this kind for other layers

OpenRA.Mods.Common/Traits/Conditions/GrantConditionOnJumpjetLayer.cs

@@ -0,0 +1,59 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	public class GrantConditionOnJumpjetLayerInfo : GrantConditionOnLayerInfo
+	{
+		public override object Create(ActorInitializer init) { return new GrantConditionOnJumpjetLayer(init.Self, this); }
+
+		public override void RulesetLoaded(Ruleset rules, ActorInfo ai)
+		{
+			var mobileInfo = ai.TraitInfoOrDefault<MobileInfo>();
+			if (mobileInfo == null || !(mobileInfo.LocomotorInfo is JumpjetLocomotorInfo))
+				throw new YamlException("GrantConditionOnJumpjetLayer requires Mobile to be linked to a JumpjetLocomotor!");
+
+			base.RulesetLoaded(rules, ai);
+		}
+	}
+
+	public class GrantConditionOnJumpjetLayer : GrantConditionOnLayer<GrantConditionOnJumpjetLayerInfo>, INotifyFinishedMoving
+	{
+		bool jumpjetInAir;
+
+		public GrantConditionOnJumpjetLayer(Actor self, GrantConditionOnJumpjetLayerInfo info)
+			: base(self, info, CustomMovementLayerType.Jumpjet) { }
+
+		void INotifyFinishedMoving.FinishedMoving(Actor self, byte oldLayer, byte newLayer)
+		{
+			if (jumpjetInAir && oldLayer != ValidLayerType && newLayer != ValidLayerType)
+				UpdateConditions(self, oldLayer, newLayer);
+		}
+
+		protected override void UpdateConditions(Actor self, byte oldLayer, byte newLayer)
+		{
+			if (!jumpjetInAir && newLayer == ValidLayerType && oldLayer != ValidLayerType && conditionToken == ConditionManager.InvalidConditionToken)
+			{
+				conditionToken = conditionManager.GrantCondition(self, Info.Condition);
+				jumpjetInAir = true;
+			}
+
+			// By the time the condition is meant to be revoked, the 'oldLayer' is already no longer the Jumpjet layer, either
+			if (jumpjetInAir && newLayer != ValidLayerType && oldLayer != ValidLayerType && conditionToken != ConditionManager.InvalidConditionToken)
+			{
+				conditionToken = conditionManager.RevokeCondition(self, conditionToken);
+				jumpjetInAir = false;
+			}
+		}
+	}
+}