Scikit-Learn compliant MERF

[Peter9192]

Hello!

First of all, thanks for developing this package and making it open source! MERF is an interesting method, and we would like to use it in one or perhaps more of our projects.

I've been playing around with my own fork of MERF to see what it would take to make MERF scikit-learn compliant. This makes it easier to use it in conjunction with other methods and procedures from sklearn and those based upon sklearn, such as pycaret. It seems to work pretty well. See the changes here

If you are interested in these changes, I could open a PR from my fork. However, this means you would have some breaking changes, and you might want to make a new major release at some point. Let me know if this is something you are interested in.

refs #64