NodeBB v4.0.0 Beta

Last friday I quietly tagged a commit on the activitypub branch with v4.0.0-beta.1, which signals that the ActivityPub integration is now ready for beta testing.

For the most complete (yet readable) list of new functionality from the alpha, check out the "Road to Beta" project page.

tl;dr — some new features and a lot of fixes

- Editing a category now issues an Update(Actor)
- replies is now populated and responds with an OrderedCollection of direct replies (see the post about that)
- Proper sharedInbox support
- Better indicators for content that comes from non-local (aka "remote") users
- Conversational context synchronization mechanic (corresponding post for that)
- Moving a topic out of the "uncategorized" category will now federate out an Announce

By and large most incompatibilties have been resolved, although if you do find some issues, please do let me know in the corresponding bug report thread.

I'm looking to wrap up the year with some of the more difficult projects I've put off

- Object Integrity Proofs, which will also enable Inbox Forwarding
- Better handling of "Open in App" signals from third-party instances
- Post visibility support (or at least better handling so non-public messages aren'y unceremoniously dropped!)
- Ongoing integration with FEPs 400e and 7888