💥 revise advice naming convention (1/2)

This is first of three big naming convention updates that have been a
long time coming. With 2.1 on the horizon, all the breaking updates will
batched together in preparation for the long haul.

In this commit, we do away with the asterix to communicate that a
function is an advice function, and we replace it with the '-a' suffix.
e.g.

  doom*shut-up -> doom-shut-up-a
  doom*recenter -> doom-recenter-a
  +evil*static-reindent -> +evil--static-reindent-a

The rationale behind this change is:

1. Elisp's own formatting/indenting tools would occasionally struggle
   with | and * (particularly pp and cl-prettyprint). They have no
   problem with / and :, fortunately.
2. External syntax highlighters (like pygmentize, discord markdown or
   github markdown) struggle with it, sometimes refusing to highlight
   code beyond these symbols.
3. * and | are less expressive than - and -- in communicating the
   intended visibility, versatility and stability of a function.
4. It complicated the regexps we must use to search for them.
5. They were arbitrary and over-complicated to begin with, decided
   on haphazardly way back when Doom was simply "my private config".

Anyhow, like how predicate functions have the -p suffix, we'll adopt the
-a suffix for advice functions, -h for hook functions and -fn for
variable functions.

Other noteable changes:
- Replaces advice-{add,remove}! macro with new def-advice!
  macro. The old pair weren't as useful. The new def-advice! saves on a
  lot of space.
- Removed "stage" assertions to make sure you were using the right
  macros in the right place. Turned out to not be necessary, we'll
  employ better checks later.

core/autoload/buffers.el

@@ -255,41 +255,6 @@ regex PATTERN. Returns the number of killed buffers."
   (doom-set-buffer-real (current-buffer) t))
 
 
-;;
-;; Advice
-
-;;;###autoload
-(defun doom*switch-to-fallback-buffer-maybe (orig-fn)
-  "Advice for `kill-current-buffer'. If in a dedicated window, delete it. If there
-are no real buffers left OR if all remaining buffers are visible in other
-windows, switch to `doom-fallback-buffer'. Otherwise, delegate to original
-`kill-current-buffer'."
-  (let ((buf (current-buffer)))
-    (cond ((window-dedicated-p)
-           (delete-window))
-          ((eq buf (doom-fallback-buffer))
-           (message "Can't kill the fallback buffer."))
-          ((doom-real-buffer-p buf)
-           (if (and buffer-file-name
-                    (buffer-modified-p buf)
-                    (not (y-or-n-p
-                          (format "Buffer %s is modified; kill anyway?" buf))))
-               (message "Aborted")
-             (set-buffer-modified-p nil)
-             (let (buffer-list-update-hook)
-               (when (or ;; if there aren't more real buffers than visible buffers,
-                      ;; then there are no real, non-visible buffers left.
-                      (not (cl-set-difference (doom-real-buffer-list)
-                                              (doom-visible-buffers)))
-                      ;; if we end up back where we start (or previous-buffer
-                      ;; returns nil), we have nowhere left to go
-                      (memq (switch-to-prev-buffer nil t) (list buf 'nil)))
-                 (switch-to-buffer (doom-fallback-buffer)))
-               (unless (delq (selected-window) (get-buffer-window-list buf nil t))
-                 (kill-buffer buf)))))
-          ((funcall orig-fn)))))
-
-
 ;;
 ;; Interactive commands
 

core/autoload/packages.el

@@ -348,7 +348,6 @@ This excludes core packages listed in `doom-core-packages'.
 If ALL-P, gather packages unconditionally across all modules, including disabled
 ones."
   (let ((noninteractive t)
-        (doom--stage 'packages)
         (doom-modules (doom-modules))
         doom-packages
         doom-disabled-packages

core/autoload/ui.el

@@ -27,12 +27,12 @@ are open."
 ;; Advice
 
 ;;;###autoload
-(defun doom*recenter (&rest _)
+(defun doom-recenter-a (&rest _)
   "Generic advisor for recentering window (typically :after other functions)."
   (recenter))
 
 ;;;###autoload
-(defun doom*shut-up (orig-fn &rest args)
+(defun doom-shut-up-a (orig-fn &rest args)
   "Generic advisor for silencing noisy functions."
   (quiet! (apply orig-fn args)))