Use buffer-name in outline paths when refiling

Buffers are made globally unique, while filename usually are not, like my
various project diaries.  This new setting allows to distinguish targets in
equally named org mode files directly when refiling (and thus also when
inserting links).

init.el

@@ -845,7 +845,7 @@
           (setq org-refile-targets '((org-agenda-files . (:maxlevel . 9))
                                      (nil . (:maxlevel . 9))
                                      (db/org-default-notes-file . (:maxlevel . 9)))
-                org-refile-use-outline-path 'file
+                org-refile-use-outline-path 'buffer-name
                 org-refile-use-cache t
                 org-refile-allow-creating-parent-nodes 'confirm
                 org-indirect-buffer-display 'current-window