doom-modeline recently switched from all-the-icons to nerd-icons, but I
cannot get it to render icons correctly. So for now I'm pinning
doom-modeline to the last commit that supported all-the-icons.
Packages that need to be loaded on emacs startup, should just be loaded
through use-package in a non-deferred manner.
It makes no real difference to startup, loading the packages either
slows down emacs before "startup" is complete, or right after it
completes. End result is that Emacs is unresponsive for basically the
same amount of time regardless.
I've been using doom-themes' doom-vibrant for long enough now that I'm
certain I won't be moving away from it anytime soon. So let's simplify
and strip away all other theme setup stuff.
