I've been doing heaps of work on the engine in the last year, but mostly only mentioning it in IRC or Discord. Better to be more public. People often never find out about new features which are only mentioned in whatsnew.txt and nowhere else, because whatsnew is too long, too much at once, and totally lacking in jokes (or maybe you used nightlies and didn't reread whatsnew when a stable version is released - unfortunately we don't always add new things to the bottom!)
I'm going to follow James' example, creating a new thread for particularly interesting new features, and post the rest here.
The things at the top of the TODO list are HotOHR requests and finally finishing the blockers for the horribly delayed
You can now copy/paste item definitions, in the individual item editor. I even added undo, because I know how horribly annoying accidentally pasting the wrong tile or spriteset is (I really need to add undo there!)
But it would be nice if you could copy/paste directly in the item browser (the slice-based "thing browser"). I'd really like all the thingbrowsers to support copy/paste, but that's a different project.
Oh... my TODO list actually read "itemedit: add add-new menu with 'copy existing' option". *grumble* guess I won't mark that off