Remove my personal kill-this-buffer and kill-this-buffer-delete-this-window functions

`(gpolonkai/kill-this-buffer)` just saved the filename of the killed buffer so it can be reopened
with `(gpolonkai/undo-buffer-kill)`.

`(gpolonkai/kill-this-buffer-delete-this-window)` is the same as the built-in
`(kill-buffer-and-window)` command, with a convenient enough key binding.

configuration.org

@@ -470,13 +470,15 @@ Copied from http://whattheemacsd.com/file-defuns.el-02.html
   nil
   "The last killed buffer.
 
-Used by `gpolonkai/kill-this-buffer' and `gpolonkai/undo-buffer-kill'.")
+Used by `gpolonkai/save-killed-buffer-filename' and `gpolonkai/undo-buffer-kill'.")
 
-(defun gpolonkai/kill-this-buffer ()
-  "Kill the current buffer, but save the buffer file name so it can be undone."
-  (interactive)
-  (setq gpolonkai/last-killed-buffer-file-name (buffer-file-name))
-  (kill-this-buffer))
+(defun gpolonkai/save-killed-buffer-filename ()
+  "Save the filename of the killed buffer in `gpolonkai/last-killed-buffer-file-name'."
+  (let ((filename (buffer-file-name)))
+   (unless filename
+    (setq gpolonkai/last-killed-bufer-file-name (buffer-file-name)))))
+
+(add-hook 'kill-buffer-hook 'gpolonkai/save-killed-buffer-filename)
 
 (defun gpolonkai/undo-buffer-kill ()
   "Undo killing the last buffer.
@@ -637,17 +639,6 @@ Copied from http://emacs-doctor.com/emacs-strip-tease.html
   (quit-window nil window))
 #+END_SRC
 
-*** Kill current buffer and delete its window
-
-#+BEGIN_SRC emacs-lisp
-(defun gpolonkai/kill-this-buffer-delete-this-window ()
-  "Kill the buffer in the current window, and then try to delete
-the current window."
-  (interactive)
-  (kill-this-buffer)
-  (delete-window))
-#+END_SRC
-
 ** ~c-mode~ related
 
 *** Copy the prototype of the current function
@@ -2933,8 +2924,7 @@ directory.  It is available from [[http://plantuml.com/download][here]].
  ("C-r" . rename-current-buffer-file)
  ("C-d" . delete-current-buffer-file)
  ("|" . toggle-window-split)
- ("k" . gpolonkai/kill-this-buffer)
- ("M-c" . gpolonkai/kill-this-buffer-delete-this-window)
+ ("k" . kill-this-buffer)
  ("M-k" . gpolonkai/undo-buffer-kill)
  ("C-b" . bury-buffer)
  ("/" . repeat)