Fix #64: Status cycling should use all "done" states

You can define several “to do” and “done” states separated by “|”:

    #+TODO: TODO NEXT STARTED | DONE CANCELLED

See `:help vimorg-todo-metadata`. You can cycle forth and back through the states using `<S-Enter>` or `<S-Left>` and `<S-Right>`. When going through the states, all “done” states should be used and not only the first one.