Reinstall fill-column-indicator

I found some advice (pun intended) on how to make it work with `avy`.

configuration.org

@@ -1786,6 +1786,13 @@ window.
   :demand
   :config
   (avy-setup-default)
+  (defadvice avy-goto-line (around avy-fci activate)
+    (let ((fci-was-on (if (boundp 'fci-mode) fci-mode nil)))
+      (when fci-was-on
+        (fci-mode -1))
+      ad-do-it
+      (when fci-was-on
+        (fci-mode 1))))
   :bind
   (("M-g c" . avy-goto-char)
    ("M-g C" . avy-goto-char-2)
@@ -2243,6 +2250,14 @@ Then configure ~real-auto-save-mode~
    ("C-c o" . ciel-co)))
 #+END_SRC
 
+** Display a line at ~fill-column~
+
+#+BEGIN_SRC emacs-lisp
+(use-package fill-column-indicator
+  :hook
+  (prog-mode . fci-mode))
+#+END_SRC
+
 * Make programming a bit easier
 
 ** Electric case