Free resources (free detached nodes from memory) (#1380)

* Free resources (free detached nodes from memory)

Found an issue when using virtualized list (https://github.com/bvaughn/react-virtualized), where unmounted react components (connected to store using connect) were not collected by the garbage collector. 
I'm not sure what is the exact explanation here, but it solved my problem.

* Fix lint issue

* Fix lint issue

* Update src/components/connectAdvanced.js

Remove comment

Co-Authored-By: Tim Dorr <timdorr@users.noreply.github.com>

src/components/connectAdvanced.js

@@ -368,6 +368,7 @@ export default function connectAdvanced(
         const unsubscribeWrapper = () => {
           didUnsubscribe = true
           subscription.tryUnsubscribe()
+          subscription.onStateChange = null
 
           if (lastThrownError) {
             // It's possible that we caught an error due to a bad mapState function, but the