🎉 Node-RED 4.0 released

Node-RED 4.0 is finally here! After a number of successful beta releases over the last couple months, we've finally got the point to make Node-RED 4.0 generally available to all. Thank you to everyone who has been involved in this release - both in contributions to the code as well as feedback on the betas. It has been a long time coming, but hopefully worth the wait.