data-dir and other flag niggles

[Haperth]

Using piper from command line (ubuntu pip installed), the --data-dir flag is totally ignored and models are downloaded to the current directory instead.

--help flag doesnt document --json-input

There is no --version flag and no version info is given by --help or --debug

[Husky2490]

I ran into the issue with the --data-dir flag as well. I suspect that argparse is appending the value supplied in the command line to the default value rather than replacing it. https://github.com/rhasspy/piper/blob/c0670df63daf07070c9be36b5c4bed270ad72383/src/python_run/piper/main.py#L61-L67 Removing the default= entry and setting it later in a similar manner to the --download-dir flag could be one way to fix the issue (shown below). If you really want to keep the current directory in the data_dir "path" (so-to-speak), you could append an else statement that appends the current directory.

    if not args.data_dir:
        # Use current directory by default
        args.data_dir = [str(Path.cwd())]

The above would need to be inserted immediately above the block handling the default condition of the --download-dir flag (below). https://github.com/rhasspy/piper/blob/c0670df63daf07070c9be36b5c4bed270ad72383/src/python_run/piper/main.py#L87-L89