add World.Clear

src/FilterStorage.cs

@@ -171,6 +171,15 @@ namespace MoonTools.ECS
 			}
 		}
 
+		// used by World.Clear, ignores callbacks
+		public void Clear()
+		{
+			foreach (var (filterSignature, entityIDs) in filterSignatureToEntityIDs)
+			{
+				entityIDs.Clear();
+			}
+		}
+
 		public void RegisterAddCallback(FilterSignature filterSignature, Action<Entity> callback)
 		{
 			addCallbacks.Add(filterSignature, callback);

src/World.cs

@@ -14,14 +14,11 @@ namespace MoonTools.ECS
 		internal readonly FilterStorage FilterStorage;
 		public FilterBuilder FilterBuilder => new FilterBuilder(FilterStorage, ComponentTypeIndices);
 
-		internal readonly ComponentDepot TemplateComponentDepot;
-
 		public World()
 		{
 			ComponentDepot = new ComponentDepot(ComponentTypeIndices);
 			RelationDepot = new RelationDepot(RelationTypeIndices);
 			FilterStorage = new FilterStorage(EntityStorage, ComponentTypeIndices);
-			TemplateComponentDepot = new ComponentDepot(ComponentTypeIndices);
 		}
 
 		public Entity CreateEntity(string tag = "")
@@ -148,6 +145,15 @@ namespace MoonTools.ECS
 			MessageDepot.Clear();
 		}
 
+		public void Clear()
+		{
+			EntityStorage.Clear();
+			MessageDepot.Clear();
+			RelationDepot.Clear();
+			ComponentDepot.Clear();
+			FilterStorage.Clear();
+		}
+
 		private Dictionary<int, int> WorldToTransferID = new Dictionary<int, int>();
 
 		// FIXME: there's probably a better way to handle Filters so they are not world-bound