Remove cursor highlighter from zimrc template
Not needed in MacOS iTerm and Terminal, (u)rxvt, termite, alacritty and
gnome-terminal.
Does it do any good in any situation?
Closes #337
The develop branch already has this out:
https://github.com/zimfw/install/blob/229cea08e5d2d6806c6bef837d67c2d7a1119744/src/templates/zimrc.zsh.erb#L83-L85