GPU optimization, performance improvements, binary output

With this release, we expose the ability to apply UniFrac to GPUs with upwards of 500x performance gains. More detail on the optimization can be found in an arXiv post, made possible thanks to the incredible efforts from @sfiligoi! While the primary focus was the adaption to GPUs, many of the improvements extend to CPUs as well.

Thank you as well to @gwarmstrong and @ChrisKeefe for contributions and testing over the past year since the last release!