Make RenderUnit require IFacing; RenderSimple can be used for crates, mines, etc; fix husk facing init

OpenRA.Game/GameRules/ActorInfo.cs

@@ -92,7 +92,7 @@ namespace OpenRA
 			while (t.Count != 0)
 			{
 				var prereqs = PrerequisitesOf(t[index]);
-				var unsatisfied = prereqs.Where(n => !ret.Any(x => x.GetType() == n || x.GetType().IsSubclassOf(n)));
+				var unsatisfied = prereqs.Where(n => !ret.Any(x => x.GetType() == n || n.IsAssignableFrom(x.GetType())));
 				if (!unsatisfied.Any())
 				{
 					ret.Add(t[index]);

OpenRA.Game/Traits/Render/RenderSimple.cs

@@ -14,13 +14,14 @@ using OpenRA.Graphics;
 
 namespace OpenRA.Traits
 {
-	public abstract class RenderSimpleInfo : ITraitInfo
+	public class RenderSimpleInfo : ITraitInfo
 	{
 		public readonly string Image = null;
 		public readonly string Palette = null;
 		public readonly string PlayerPalette = "player";
 		public readonly float Scale = 1f;
-		public abstract object Create(ActorInitializer init);
+
+		public virtual object Create(ActorInitializer init) { return new RenderSimple(init.self); }
 
 		public virtual IEnumerable<Renderable> RenderPreview(ActorInfo building, Player owner)
 		{
@@ -30,7 +31,7 @@ namespace OpenRA.Traits
 		}
 	}
 
-	public abstract class RenderSimple : IRender, ITick
+	public class RenderSimple : IRender, ITick
 	{
 		public Dictionary<string, AnimationWithOffset> anims = new Dictionary<string, AnimationWithOffset>();
 
@@ -70,6 +71,11 @@ namespace OpenRA.Traits
 			Info = self.Info.Traits.Get<RenderSimpleInfo>();
 		}
 
+		public RenderSimple(Actor self) : this( self, MakeFacingFunc(self) )
+		{
+			anim.PlayRepeating("idle");
+		}
+
 		public string Palette(Player p) { return Info.Palette ?? Info.PlayerPalette + p.InternalName; }
 
 		public virtual IEnumerable<Renderable> Render(Actor self)

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -132,12 +132,14 @@ namespace OpenRA.Traits
 
 	public interface IMove : ITeleportable { int Altitude { get; set; } }
 
-    public interface IFacing
-    {
-        int ROT { get; }
-        int Facing { get; set; }
-        int InitialFacing { get; }
-    }
+	public interface IFacing
+	{
+		int ROT { get; }
+		int Facing { get; set; }
+		int InitialFacing { get; }
+	}
+
+	public interface IFacingInfo {}		/* tag interface for infoclasses whose corresponding trait has IFacing */
 
     public interface ICrushable
     {
@@ -181,7 +183,7 @@ namespace OpenRA.Traits
 
     public class TraitInfo<T> : ITraitInfo where T : new() { public virtual object Create(ActorInitializer init) { return new T(); } }
 
-    public interface Requires<T> where T : ITraitInfo { }
+    public interface Requires<T> where T : class { }
 
     public interface INotifySelection { void SelectionChanged(); }
     public interface IWorldLoaded { void WorldLoaded(World w); }

OpenRA.Game/Traits/World/PlayerColorPalette.cs

@@ -10,6 +10,7 @@
 
 using OpenRA.FileFormats;
 using OpenRA.Graphics;
+
 namespace OpenRA.Traits
 {	
 	public class PlayerColorPaletteInfo : ITraitInfo
@@ -25,6 +26,7 @@ namespace OpenRA.Traits
 	{
 		readonly Player owner;
 		readonly PlayerColorPaletteInfo info;
+
 		public PlayerColorPalette( Player owner, PlayerColorPaletteInfo info )
 		{
 			this.owner = owner;