sh: reset sh bindings on bind -e, bind -v

Until this change, any bindings set in histedit() were lost on calls to
bindcmd().

Only bind -e and bind -v call libedit's keymacro_reset(). Currently you
cannot fool libedit/map.c:map_bind() by trying something like bind -le
as when p[0] == '-', it does a switch statement on p[1].