How are MDK3 and MDK4 different? What's new with this new version?

[Mortuus-Medicus]

I haven't used MDK tool for quite some time now, I think it was still version 2 when I last used it.
But now that I want to use it again, I noticed that it's already at a version 4, but no where in the Read Me does it say what's actually different, why is version 4 better then version 3?

Thanks!