The tool looks really promising, and I'd love to see it develop into an alternative to working with Sprytile.
Some thoughts I had as I used it :
* Mention in the docs that you need to be in SceneView to start working
* Mention in the docs that after creating the Custom Mesh or adding the MeshEdit script, you need to add a MeshFilter/MeshRenderer on the same game object.
* Mention in the docs that you need to add a material to the MeshRenderer to start tile painting
* Mention in the docs that to paint with multiple tilesets that you can load them as subsequent textures in the Window>Tilesets
* Face selection in the Tile Edit mode doesn't have the dots like MeshEdit mode has, so it's really difficult to tell which face is selected for painting.
* I'd really love if the Tile Edit mode had a dotted outline around the face you are painting, or if as the mouse moved it put an outline around the face that will get painted.
* The vertex paint mode is a bit too slow to be usable at the moment.
Overall though, this is a really neat tool, and I appreciate the hard work you put into it!