Do not define empty non-virtual destructors

[danielkrupinski]

Providing an empty definition of a non-virtual destructor is pointless, as the compiler can implicitly provide the definition itself. Moreover, it makes a type non-trivially destructible what prevents the compiler from applying certain optimizations (this isn't the case in this PR).

[adam-sawicki-a]

Thank you for this contribution. You are right. I only don't like that you remove the comments from the destructors. They are meaningful. I think they should be preserved, possibly moved to class definition next to e.g. commented destructor like:

// Comment
//~List() { }

[adam-sawicki-a]

Thank you for this contribution!

[danielkrupinski]

More are incoming :)