Make cloning entries work at the end of the buffer

Make cloning entries work at the end of the buffer

David Maus writes:

> By accident I noticed that if you clone a subtree using C-c C-x c who
> or whose content is the last line of the file orgmode inserts the
> clone without the desired newline.
>
> example.org
> ,----
> | * Just a test
> `----
>
> If you move the point behind test and press C-c C-x c 1 <RET> <RET>
> the clone is inserted right behind "test".
>
> example.org
> ,----
> | * Just a test*Just a test
> `----
>
> Instead orgmode should insert a newline before inserting the clone
> when the file misses an empty line at the end.