Remove spurious tabs in config files and ensure they don't reappear

Closes #465

.dir-locals.el

@@ -0,0 +1,5 @@
+;;; Directory Local Variables
+;;; For more information see (info "(emacs) Directory Variables")
+
+((emacs-lisp-mode
+  (indent-tabs-mode . nil)))

lisp/init-editing-utils.el

@@ -260,10 +260,10 @@ on the new line if the line would have been blank.
 With arg N, insert N newlines."
   (interactive "*p")
   (let* ((do-fill-prefix (and fill-prefix (bolp)))
-	 (do-left-margin (and (bolp) (> (current-left-margin) 0)))
-	 (loc (point-marker))
-	 ;; Don't expand an abbrev before point.
-	 (abbrev-mode nil))
+         (do-left-margin (and (bolp) (> (current-left-margin) 0)))
+         (loc (point-marker))
+         ;; Don't expand an abbrev before point.
+         (abbrev-mode nil))
     (delete-horizontal-space t)
     (newline n)
     (indent-according-to-mode)
@@ -272,8 +272,8 @@ With arg N, insert N newlines."
     (goto-char loc)
     (while (> n 0)
       (cond ((bolp)
-	     (if do-left-margin (indent-to (current-left-margin)))
-	     (if do-fill-prefix (insert-and-inherit fill-prefix))))
+             (if do-left-margin (indent-to (current-left-margin)))
+             (if do-fill-prefix (insert-and-inherit fill-prefix))))
       (forward-line 1)
       (setq n (1- n)))
     (goto-char loc)

lisp/init-python-mode.el

@@ -1,6 +1,6 @@
 (setq auto-mode-alist
       (append '(("SConstruct\\'" . python-mode)
-		("SConscript\\'" . python-mode))
+                ("SConscript\\'" . python-mode))
               auto-mode-alist))
 
 (require-package 'pip-requirements)

lisp/init-sessions.el

@@ -20,7 +20,7 @@
                (sanityinc/time-subtract-millis (current-time)
                                                start-time)
                (when filename
-		 (abbreviate-file-name filename))))))
+                 (abbreviate-file-name filename))))))
 
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