This function, given all arguments, simply flashes the image

This function simply shows the command line arguments

This function finds the USB device with USB vendor/product IDs.
Multiple identical products can be differentiated with the serial
number, if needed.

The matching device, if unique, is referenced and returned.

This error code captures higher-level errors than what libusb returns
alone. It also has a dedicated code for libusb errors.

Otherwise include paths aren't neccessarily found by the compiler.

Fix link error

This is important for the program to also be portable to Windows.

This happens e.g. when the checksum is incorrect, but not for much else.