Cache sync hash functions per actor for faster sync calculations.

Caching the result of the function lookup allows the actor to calculate all the sync hashes for its syncable traits faster as it does not need to repeat the lookup each time.

OpenRA.Game/Actor.cs

@@ -24,6 +24,13 @@ namespace OpenRA
 {
 	public sealed class Actor : IScriptBindable, IScriptNotifyBind, ILuaTableBinding, ILuaEqualityBinding, ILuaToStringBinding, IEquatable<Actor>, IDisposable
 	{
+		internal struct SyncHash
+		{
+			public readonly ISync Trait;
+			public readonly int Hash;
+			public SyncHash(ISync trait, int hash) { Trait = trait; Hash = hash; }
+		}
+
 		public readonly ActorInfo Info;
 
 		public readonly World World;
@@ -62,6 +69,8 @@ namespace OpenRA
 			}
 		}
 
+		internal IEnumerable<SyncHash> SyncHashes { get; private set; }
+
 		readonly IFacing facing;
 		readonly IHealth health;
 		readonly IRenderModifier[] renderModifiers;
@@ -112,6 +121,12 @@ namespace OpenRA
 			visibilityModifiers = TraitsImplementing<IVisibilityModifier>().ToArray();
 			defaultVisibility = Trait<IDefaultVisibility>();
 			Targetables = TraitsImplementing<ITargetable>().ToArray();
+
+			SyncHashes =
+				TraitsImplementing<ISync>()
+				.Select(sync => Pair.New(sync, Sync.GetHashFunction(sync)))
+				.ToArray()
+				.Select(pair => new SyncHash(pair.First, pair.Second(pair.First)));
 		}
 
 		Rectangle DetermineBounds()