Implement SmoothSort

[nlw0]

There's a PR open for comb sort (#54). I would like to submit an implementation for smoothsort next. Perhaps the greatest feature of smoothsort is that it performs well for approximately sorted inputs, like insertion sort tends to do, but smoothsort is O(n log n). It might make a good pairing with combsort.

I'm still investigating how well this implementation works, but I have a draft here, and it would be great to hear some feedback already. Especially because this is a slightly complicated algorithm. Does that look good? Should I just go ahead and start another PR, or is there some big issue I should try to figure out first?

https://gist.github.com/nlw0/6c56d7660fb1c5fa71cef654b9c25db2