Use %D for date.
Simplify notes-push.
Simplify notes-pull.
Let message2url copy.

I've also changed the url format to use message://. I think that's the simplier
format.
Fix thread uris.
Simplify notes-store.
Simplify notes-setup.
Setup exits if directory exists.
Write errors to stderr.
Simplify todo-cli.
Add documentation to todo-code.