* fix error
* remove options that are no longer supported
* add missing options
* stop completion if an option `--help` or `--version` is supplied
[[[
zjs: a note for the reader:
zshcompsys(1) in the section about optspecs in _arguments says:
> Each of the forms above may be preceded by a list in parentheses of option names and argument num‐
> bers. If the given option is on the command line, the options and arguments indicated in parentheses
> will not be offered. For example, ‘(-two -three 1)-one:...' completes the option ‘-one'; if this ap‐
> pears on the command line, the options -two and -three and the first ordinary argument will not be
> completed after it. ‘(-foo):...' specifies an ordinary argument completion; -foo will not be com‐
> pleted if that argument is already present.
>
> Other items may appear in the list of excluded options to indicate various other items that should
> not be applied when the current specification is matched: a single star (\*) for the rest arguments
> (i.e. a specification of the form ‘\*:...'); a colon (:) for all normal (non-option-) arguments; and a
> hyphen (-) for all options. For example, if ‘(\*)' appears before an option and the option appears on
> the command line, the list of remaining arguments (those shown in the above table beginning with
> ‘\*:') will not be completed.
The intended effect of the change is to remove irrelevant completion matches from the completion.
tl;dr: (- : ) prevents further completion
]]]
Things like -n to specify the lines to show with systemctl and
journalctl accepts syntax like:
journalctl -n4
systemctl -n14
Previously, typing `-nXX <tab>` where XX is a number, zsh would try to
complete an integer. Now it will see the XX and use the _journalctl_none
completion. This is also how any of the single letter options that take
arguments work as well.
_hosts_or_user_at_host was used by 6 different completions, and
previously was in all 6 of those files. I moved it out to its own file,
_sd_hosts_or_user_at_host. This will be autoloaded for use in other
completion functions. It also allows external completions to use this
function by simply calling _sd_hosts_or_user_at_host as in the systemd
completions.
