Use a BitSet for representing target types.

- Rename Bits<T> to BitSet<T>.
- Implement set based helpers for BitSet<T>.
- When representing TargetTypes of ITargetable in various traits, use a BitSet<TargetableType> instead of HashSet<string> for better performance & reduced memory usage.
- Fix FieldLoader to trim input values when generating a BitSet<T>.
- Require T in BitSet<T> and BitSetAllocator<T> to be a class since it's just a marker value. This allows the JIT to instantiate generic code for these classes once, as they don't benefit from specialized code for T. (Typically JITs will generate shared code for all reference types, and unique code for every value type encountered).

OpenRA.Mods.Cnc/Traits/Disguise.cs

@@ -16,6 +16,7 @@ using System.Linq;
 using OpenRA.Mods.Common.Orders;
 using OpenRA.Mods.Common.Traits;
 using OpenRA.Mods.Common.Traits.Render;
+using OpenRA.Primitives;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.Cnc.Traits
@@ -84,7 +85,7 @@ namespace OpenRA.Mods.Cnc.Traits
 		public readonly Stance ValidStances = Stance.Ally | Stance.Neutral | Stance.Enemy;
 
 		[Desc("Target types of actors that this actor disguise as.")]
-		public readonly HashSet<string> TargetTypes = new HashSet<string> { "Disguise" };
+		public readonly BitSet<TargetableType> TargetTypes = new BitSet<TargetableType>("Disguise");
 
 		[Desc("Triggers which cause the actor to drop it's disguise. Possible values: None, Attack, Damaged,",
 			"Unload, Infiltrate, Demolish, Move.")]
@@ -317,7 +318,7 @@ namespace OpenRA.Mods.Cnc.Traits
 			if (!info.ValidStances.HasStance(stance))
 				return false;
 
-			return info.TargetTypes.Overlaps(target.Info.TraitInfos<ITargetableInfo>().SelectMany(ti => ti.GetTargetTypes()));
+			return info.TargetTypes.Overlaps(target.Info.GetAllTargetTypes());
 		}
 	}
 }