cleanup

TODO

@@ -39,5 +39,3 @@
 * observer: user defined filters (eg .replace<T, &function> or .group<T, U, &func>)
 * any-of rule for views/groups (eg entity has A and any of B/C/D)
 * sparse set: there exists an alternative to paginated sparse arrays?
-* meta
-  - update doc

src/entt/entity/registry.hpp

@@ -14,7 +14,6 @@
 #include "../core/family.hpp"
 #include "../core/algorithm.hpp"
 #include "../core/type_traits.hpp"
-#include "../signal/delegate.hpp"
 #include "../signal/sigh.hpp"
 #include "runtime_view.hpp"
 #include "sparse_set.hpp"