The logic that was tested in the previous commit is used to implement
the behaviour for unit-shell and other verbs without changes.
The compare-versions synopsis is shortened to "V1 [OP] V2" to make the
verb synopsis fit. Unusual capitalizaition of "Command" is changed to
"COMMAND" (it's a replace arg, not a fixed string), and some help
strings are adjusted. The order of options in --help is based on the
existing order in parse_argv(). The old order in --help was mostly
random. I think it might be good to figure out something more rational
here, but I'm leaving that as a separate step.
The urlification of dot(1) in the --help string is lost. It's hard to
do this with the help string being stored in a read-only section.
I think this is not worth the trouble to reimplement in the current
scheme.