Replace org-bullets w/ org-superstar

org-superstar is a little faster, better written and still maintained.
It also has a few more features which I've made opt-in because they are
relatively expensive in larger buffers.

Folks that don't care for the differences just have to replace
`org-bullets-bullet-list` in their configs with
`org-superstar-headline-bullets-list`.

modules/lang/org/config.el

@@ -759,8 +759,22 @@ compelling reason, so..."
         (set-marker p nil)))))
 
 
-(use-package! org-bullets ; "prettier" bullets
-  :hook (org-mode . org-bullets-mode))
+(use-package! org-superstar ; "prettier" bullets
+  :hook (org-mode . org-superstar-mode)
+  :config
+  ;; Make leading stars truly invisible, by rendering them as spaces!
+  (setq org-superstar-leading-bullet ?\s
+        org-hide-leading-stars nil)
+  ;; Don't do anything special for item bullets or TODOs by default; these slow
+  ;; down larger org buffers.
+  (setq org-superstar-prettify-item-bullets nil
+        org-superstar-special-todo-items nil
+        ;; ...but configure it in case the user wants it later
+        org-superstar-todo-bullet-alist
+        '(("TODO" . 9744)
+          ("[ ]"  . 9744)
+          ("DONE" . 9745)
+          ("[X]"  . 9745))))
 
 
 (use-package! org-crypt ; built-in