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
linum-mode *really* slows down buffers when they're displayed in more
than one window. This lag isn't present in nlinum. nlinum isn't perfect
either but... lesser of two evils.
This includes advisors and an ESC hook to mitigate the issue of
disappearing nlinum line numbers.
