Fix super constructor not being called / required to be called

[dcodeIO]

This is a tracking issue for super(...) calls in constructors, which doesn't work currently for no good reason.

[dcodeIO]

Also: Document limitations of virtual (here: overloaded) members due to virtual lookup tables not being implemented yet (here: missing runtime type information), i.e.

class A {
  foo(): i32 { return 0; }
}
class B extends A {
  foo(): i32 { return 1; }
}

(new B() as A).foo() == 0

[MaxGraey]

@dcodeIO Is this issue still present?