1. Why is `libusb-1.0.dll` bundled for MacOS and Windows? Note: I'm not question this, just
want to learn why. Are they not installed by pip if listed as a requirement?
2. If I understand it correctly, command `dfu usb-serial` is identical to `dfu serial` except `dfu usb-serial` do not ping!? The documentation and help page seems to indicate other differences but I do not find any evidence for this in current code base. Perhaps `usb-serial` option and related code could be removed to avoid further confusion? (I suspect most serial interfaces are USB nowadays...). In `argparse` it would be possible to keep it as a hidden alias for backward compatible but it doesn't seem possible with `click` from what I can tell.
