Remove project from list, and ask for removing files from disk

Maybe it's clearer if we say `"Do you want to permanently delete all files in " + app.location + "?"` so it's clear that "erase the data" means "remove the entire directory" and we double-check which directory.

Another nice thing would be to make the confirm buttons say "Remove" and "Erase" (or other verbs) instead of OK or Yes.