zle automatically calls zle-line-init when it starts to read a new line. Many
Zsh setups use this hook to set the terminal into application mode, since this
will then allow defining keybinds based on the $terminfo variable (the escape
codes in said variable are only valid in application mode).
However, fzf resets the terminal into raw mode, rendering $terminfo values
invalid once the widget has finished. Accordingly, keyboard bindings defined
via $terminfo won’t work anymore.
This fixes the issue by calling zle-line-init when widgets finish. Care is taken
to not call this widget when it is undefined.
Fixes#279
