Cleanup typecasts and compiler warnings regarding typecasts

[Zomis]

A lot of places are marked with e.g. Unchecked cast: ActionTypeImplEntry<T, Any> to ActionTypeImplEntry<T, A>

This can be cleaned up in many cases by marking the appropriate type parameters in the right places with either out or in (usually out)

[Zomis]

See also https://kotlinlang.org/docs/generics.html