I'm not fully convinced with swapping out ido with selectrum, so I'll
add the configuration for both, without actually loading them, and
instead manually try them out from time to time.
Also, make ivy use prescient for filtering and sorting, as it does a
much better job than ivy itself does by default. But nothing currently
uses ivy either, so it's more for future if I start using ivy somewhere.
There are a few major modes which are not based on prog-mode, that I
want to behave like prog-mode. Previously each did nearly all the same
setup that's done via the prog-mode hooks. Now instead let's actually
run runs the hooks for prog-mode.
The original code to fix the incompatibility didn't see to work anymore,
so refactored it a bit to so it goes about things a bit more carefully,
and that seemed to fix it.
