Major optimization refactor, across the board

+ enable lexical-scope everywhere (lexical-binding = t): ~5-10% faster
  startup; ~5-20% general boost
+ reduce consing, function calls & garbage collection by preferring
  cl-loop & dolist over lambda closures (for mapc[ar], add-hook, and
  various cl-lib filter/map/reduce functions) -- where possible
+ prefer functions with dedicated opcodes, like assq (see byte-defop's
  in bytecomp.el for more)
+ prefer pcase & cond (faster) over cl-case
+ general refactor for code readability
+ ensure naming & style conventions are adhered to
+ appease byte-compiler by marking unused variables with underscore
+ defer minor mode activation to after-init, emacs-startup or
  window-setup hooks; a customization opportunity for users + ensures
  custom functionality won't interfere with startup.

modules/ui/hl-todo/config.el

@@ -1,9 +1,8 @@
-;;; ui/hl-todo/packages.el
+;;; ui/hl-todo/packages.el -*- lexical-binding: t; -*-
 
 (def-package! hl-todo
   :commands hl-todo-mode
-  :init
-  (add-hook 'prog-mode-hook #'hl-todo-mode)
+  :init (add-hook 'prog-mode-hook #'hl-todo-mode)
   :config
   (setq hl-todo-keyword-faces
         `(("TODO"  . ,(face-foreground 'warning))