[tor-relays] Summary of v0.2.3.x --> v0.2.4.x changes?

[Steve Snyder]

Now that Tor v0.2.4.x has reached Release Candidate status, could someone please inform those who haven't been following the development process what is new?

I just mean the broad strokes.  Like: What changes to a working relay are required or recommended when moving to v0.2.4.x?

What are the major new features of this release?  (Any benefit now to using more than 2 CPU cores?  IPv6 support for non-bridge relays?  That sort of thing.)

Thanks.