-Events system update order is now choosen according to system priority

-added mixin for adding exluded components using it's type
-demos:
 *added GUI for selecting templates and choosing tools
 *change SpaceInvades SideMove system to not using events for better performance and multithreading
 *added Entites spawning support
 *fixed some Snake demo bugs
 *GUI work's better now

source/ecs/core.d

@@ -21,4 +21,9 @@ static struct ECS
 		__gshared ushort event_id;
 		EntityID entity_id;
 	}
+
+	mixin template ExcludedComponents(T...)
+	{
+		alias ExcludedComponents = T;
+	}
 }