Calibration

[Glavin001]

I have noticed that there are a couple issues regarding the mis-calibration of quietnet.
See #3, #14 for those that I've read.

Given that listen.py and send.py are separate scripts, a third script should be able to run those in a controlled way, sending various messages through send.py and validating the received result in listen.py and subsequently adjusting the threshold and frame_length, etc, and then re-running the tests until the result is accurate.

To make this plausible, there would have to be a distinct configuration file (currently options.py, although threshold must be moved within there, too) that could be edited and reloaded. Also, the listen.py and send.py would be to be able to be used by another Python script, the calibrator.py for instance.

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@Katee, I'd be up for creating a Pull Request, if you like the idea. I will need some guidance, both because I'm relatively inexperienced with Python and also because I believe this will require some major refactoring, so I'd definitely want your input on that 😄.