Positional args should also be kebab-cased in the help output

[Boscop]

Currently the usage prints positional args in snake_case, e.g.:

Usage: D:\foo.exe [<project_file>] [-t <time-offset>] [<command>] [<args>]

It should also print positional args in kebab-case for consistency (project-file in this case).

[benbrittain]

what is happening here is that it kebab cases the "long" name if the long is omitted.