💥 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/tools/neotree/config.el

@@ -33,5 +33,9 @@
           "~$"
           "^#.*#$"))
 
+  (set! :popup "^ ?\\*NeoTree"
+    `((side . ,neo-window-position) (width-width . ,neo-window-width))
+    '((escape-quit . current) (select . t)))
+
   (when (bound-and-true-p winner-mode)
     (push neo-buffer-name winner-boring-buffers)))