fix trait ordering, via ITraitPrerequisite<>. We'll need to do this for other traits, later (I've just fixed the crashbug)

OpenRa.Game/Actor.cs

@@ -39,7 +39,7 @@ namespace OpenRa
 				Info = Rules.Info[name.ToLowerInvariant()];
 				Health = this.GetMaxHP();
 
-				foreach (var trait in Info.Traits.WithInterface<ITraitInfo>())
+				foreach (var trait in Info.TraitsInConstructOrder())
 					traits.Add(trait.Create(this));
 			}
 		}

OpenRa.Game/GameRules/ActorInfo.cs

@@ -79,5 +79,39 @@ namespace OpenRa.GameRules
 
 			throw new InvalidOperationException("Cannot locate trait: {0}".F(traitName));
 		}
+
+		public IEnumerable<ITraitInfo> TraitsInConstructOrder()
+		{
+			var ret = new List<ITraitInfo>();
+			var t = Traits.WithInterface<ITraitInfo>().ToList();
+			int index = 0;
+			while( t.Count != 0 )
+			{
+				if( index >= t.Count )
+					throw new InvalidOperationException( "Trait prerequisites not satisfied (or prerequisite loop)" );
+
+				var prereqs = PrerequisitesOf( t[ index ] );
+				if( prereqs.Count == 0 || prereqs.All( n => ret.Any( x => x.GetType().IsSubclassOf( n ) ) ) )
+				{
+					ret.Add( t[ index ] );
+					t.RemoveAt( index );
+					index = 0;
+				}
+				else
+					++index;
+			}
+
+			return ret;
+		}
+
+		static List<Type> PrerequisitesOf( ITraitInfo info )
+		{
+			return info
+				.GetType()
+				.GetInterfaces()
+				.Where( t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof( ITraitPrerequisite<> ) )
+				.Select( t => t.GetGenericArguments()[ 0 ] )
+				.ToList();
+		}
 	}
 }

OpenRa.Game/Traits/RenderBuildingWarFactory.cs

@@ -4,7 +4,7 @@ using OpenRa.Graphics;
 
 namespace OpenRa.Traits
 {
-	class RenderWarFactoryInfo : ITraitInfo
+	class RenderWarFactoryInfo : ITraitInfo, ITraitPrerequisite<RenderSimpleInfo>
 	{
 		public object Create(Actor self) { return new RenderWarFactory(self); }
 	}

OpenRa.Game/Traits/TraitsInterfaces.cs

@@ -94,4 +94,5 @@ namespace OpenRa.Traits
 		public object Create(Actor self) { return Instance.Value; }
 	}
 
+	interface ITraitPrerequisite<T> { }
 }