Just binding ^[[A/^[[B does not work for some terminals, while not
binding them breaks zle widgets on other terminals. That's how crazy it
can get :- (
Fixes#293. Fixes#295.
See https://github.com/zsh-users/zsh-history-substring-search/issues/70
and comment by @molovo:
I was already binding keys _after_ `zle-line-init`, but I'm pulling
keycodes out of the `terminfo` module, which reports up
(`$terminfo[kcuu1]`) as `^[0A` instead of `^[[A`. Binding `^[[A`
manually mean up/down works with history-substring-search both
before and after `zle-line-init`, but if I bind `$terminfo[kcuu1]`
(`^[0a`), up/down only works *before* `zle-line-init`.
Closes#286
