There's a new much nicer template editor that uses the open source Ace editor. It's the same editor that GitHub uses. It's got some great features. It's not an outliner, and for some people that's a good thing.
Here's a screen shot.
If you're using my.1999.io to do your blogging, you already have the new template editor. When you choose it from the PlugIns menu, you'll get the new editor.