Consider deprecating this library in favor of the `libusb` crate

[kevinmehall]

This library was written in 2013 in a language that was called Rust, but was very different than the language we know as Rust 1.0. Specifically, it had green-threaded IO, and it lacked today's conventions around error handling. This library has been updated along the way just enough to keep compiling, but would effectively be a different library if written in modern Rust.

@dcuddeback has effectively written that library.

A future possibility for the usb crate name could be to implement common USB patterns on top of the libusb crate and Libusb itself, such as:

• finding devices and interfaces with descriptors that match certain criteria
• maximizing streaming throughput by stacking asynchronous transfers
• delimiting logical frame boundaries with zero-length packets