Cleanup completion buffers

I could do that with many other buffers I dislike

init.el

@@ -315,6 +315,13 @@ This is the same as using \\[set-mark-command] with the prefix argument."
 ;; (require 'smartparens-config)
 ;; (require 'smartparens-latex)
 
+(add-hook 'minibuffer-exit-hook
+          '(lambda ()
+             (let ((buffer "*Completions*"))
+               (and (get-buffer buffer)
+                    (kill-buffer buffer)))
+	     ))
+
 (setq server-name (kde-current-activity))
 (server-start)
 (menu-bar-mode -99)