Techincally, there is an editor. Notepad.
You can edit XML, Python, soon SDK, and even worldbuilder maps with lowly notepad. For making maps, you need, I believe, 5 images now, and run a python script. But... you can simply save a game in Worldbuilder, save the worldbuilder save, and then edit that file in notepad (i.e., to add extra civs, etc.). You can then edit the map again in worldbuilder as you see fit.
