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/lang/swift/config.el

@@ -1,4 +1,4 @@
-;;; lang/swift/config.el
+;;; lang/swift/config.el -*- lexical-binding: t; -*-
 
 ;; TODO Set up emacs task runners for fruitstrap
 
@@ -8,7 +8,7 @@
   (add-hook 'swift-mode-hook #'flycheck-mode)
   :config
   (set! :repl 'swift-mode #'swift-mode-run-repl) ; TODO test this
-  (push 'swift flycheck-checkers))
+  (cl-pushnew 'swift flycheck-checkers))
 
 
 (def-package! company-sourcekit