min-class-cohesion: possibility to specify metrics algorithm

[pesoklp13]

It would be nice be able to choose metrics to calculate cohesion. See http://www.math.md/files/csjm/v25-n1/v25-n1-(pp44-74).pdf

[Glavin001]

Awesome idea! Pull Requests are very welcome 🎉 .

[pesoklp13]

Hope i will find some time to make some algorithm