bug: Self/self-reference incomplete

[phorward]

This bug came from further investigation into #127.

---

A: @<E, I: Self> {
    Ident '=' Expect<I>  # (1)
    E
}

A<Int>                   # (2)
A<Int, Self>             # (3)

Expected result:

• Expect<P> is a prelude base parselet, no instance
• A<E, I: Self> is a base parselet, no instance
• (2) A<E: Int, I: Self> derives (1) Expect<A<E: Int, I: Self>>
• (3) A<E: Int, I: __main__> derives (1) Expect<A<E: Int, I: __main__>>

Current (buggy) implementation:

• ImlParseletModel is created once for Expect and A
• ImlParselet (and ImlRefParselet) is created for
  • Expect<P>
  • Expect<Self>
  • A<E, I: Self>
  • A<E: Int, I: Self> where Self should refer to the self-recusive parselet instance, but this information is lost, and
  • A<E: Int, I: Self> where Self refers to __main__, and Self currently is __main__ everywhere, so that imaginary
    • A<E: Int, I: __main__> and
    • Expect<__main__> is constructed and executed.
• The derives are only created from the parselet which is currently compiled or finalized:
  • src/compiler/iml/imlprogram.rs 187,43: let derived = parselet.derive(current).unwrap();
  • src/tokay/src/compiler/iml/imlvalue.rs 401,63: ImlValue::Parselet(parselet) => match parselet.derive(current.0) {