Adding the OPTICS clustering algorithm

[cmccomb]

Getting started on implementing OPTICS in response to issue #52

[Mec-iS]

hey @cmccomb are you still interested in completing this? I would be glad to help out. If you think is ready, click the "Ready for review" button.

[cmccomb]

Hey @Mec-iS! I don't have the bandwidth to work on this. I'd actually forgotten that I volunteered to do it. Sorry!

[Mec-iS]

@cmccomb
no problem. You may be interested to know that we are revamping the library, you can check the notebooks for the new coming version at https://github.com/smartcorelib/smartcore-jupyter/tree/main/notebooks

Please just annotate down here what is done and what is missing in this PR so we can pick it up.
Thanks for your contribution.

[cmccomb]

Thanks! To be honest, not much is done - I started to rough out some code based on another algorithm but only got as far as some basic refactoring. It might be better to make a clean start.