Georgii Kovalev

Fixed more complex cases for union and intersection types Fixes #516

- [x] Rewrited current derivation to make it simple and remove experimental staff. And everything gone to core module. - [x] Old derivation is fully deprecated. Old enum derivation is...

Hello, not sure if this is a bug. Extension method `=:=` do not see typeclass instances put in typeclass companion object, it feels not very clear why should I use...