Equatable structs should not include type inheritance

[angelolloqui]

An Equatable struct does not need to implement Equatable in Kotlin since dataclasses are already equatable by default.

This code:

struct User: Equatable {    
    var id: Int? = 0
    var name: String?
}

must be translated to:

data class User(
    var id: Int? = 0,
    var name: String? = null) {}

Instead of:

data class User(
    var id: Int? = 0,
    var name: String? = null): Equatable {}

[angelolloqui]

Fixed with #109