💥 Replace core-popup with new feature/popup module

This is a breaking change! Update your :popup settings. Old ones will
throw errors!

Doom's new popup management system casts off its shackles (hur hur) and
replaces them with the monster that is `display-buffer-alist`, and
window parameters.

However, this is highly experimental! Expect edge cases.  Particularly
with org-mode and magit (or anything that does its own window
management).

Relevant to #261, #263, #325

modules/feature/debugger/config.el

@@ -3,9 +3,7 @@
 (def-package! realgud
   :commands (realgud:gdb realgud:trepanjs realgud:bashdb realgud:zshdb)
   :config
-  (set! :popup
-     '("^\\*\\(g\\|zsh\\|bash\\)db.*?\\*$" :size 20 :regexp t)
-     '("^\\*trepanjs.*?\\*$"               :size 20 :regexp t))
+  (set! :popup "^\\*\\(?trepanjs:\\(?:g\\|zsh\\|bash\\)db\\)" '((size . 20)))
 
   ;; TODO Temporary Ex commands for the debugger
   ;; (def-tmp-excmd! doom:def-debug-on doom:def-debug-off