Honor option '--help'

[gvanem]

After installing the requirements with pip3.exe install -U pyModeS pyrtlsdr and issuing a py.exe -3 pyModeS\streamer\modeslive.py --help, all I get is:

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Warning: pyrtlsdr not installed (required for using RTL-SDR devices)!
---------------------------------------------------------------------

I'd assume some sensible help regardless of some import error. But nothing. This is one confusing package IMHO. Is it really for Windows at all?