This takes care of my outstanding TODO of understanding why something ivy was
being used and other times it wasn't. It turns out that there is a generic
`completing-read` function that many Emacs packages consume. `ivy-mode` ensures
that when that function is called it is used instead of the default Emacs
completing package.
I'm still unsure of the difference between ivy and counsel. My best guess
currently is that counsel is the narrowing framework and ivy is the integration
of the narrowing framework with `completing-read`. Swiper must be the
integration with incremental {forward,backward} search.
d1fdc9fa63