Adding to NetworkX

[cmeb45]

Hi @53RT,

I've tried out the functions in this repo and they are very useful. Would you be open to contributing this work to the main NetworkX repo, or to others doing so (there do not appear to be any issues or pull requests in NetworkX involving HCS)? I've pulled it down and made a few changes on my end, so I don't mind doing so myself, and would of course give you credit.

Thanks in advance.