Major refactor of Doom bootstrap process

+ New `input` and `buffer` support for :defer in def-package! can now
  defer packages until the first command invoked after startup or first
  interactive buffer switch, respectively
+ Exploit these new :defer techniques to lazy-load many core packages,
  netting Doom a 20-30% decrease in startup time
+ Various userland macros (like package!, def-package-hook!, packages!,
  and disable-packages!) will now throw an error if used incorrectly
  (i.e. outside of their intended files; e.g. package! should be used in
  packages.el files)
+ Removed support for multiple/nested doom! calls. There should only be
  THE ONE in ~/.doom.d/init.el (or ~/.config/doom/init.el)
+ Fix an issue where load-path and auto-mode-list modifications would
  not persist because doom-packages-file was cached too late.
+ Added package-activated-list to cached variables in
  doom-packages-file, thus we no longer need custom-file.
+ Load Doom core files from doom-initialize. Now doom-initialize can be
  called from state-dependent non-interactive functions, instead of
  reloading core/core.el, which was clumsy
+ Removed the doom-post-init-hook hook. There was no reason for it to
  exist when doom-init-hook can simply be appended to

core/core-projects.el

@@ -12,9 +12,9 @@
         projectile-ignored-projects '("~/" "/tmp"))
 
   :config
-  (projectile-mode +1)
   (add-hook 'dired-before-readin-hook #'projectile-track-known-projects-find-file-hook)
   (add-hook 'find-file-hook #'doom|autoload-project-mode)
+  (projectile-mode +1)
 
   ;; a more generic project root file
   (push ".project" projectile-project-root-files-bottom-up)