[NEXT] Iterators

[Sir-NoChill]

I know @rcunrau has been pushing to get to this point, and I think it may be possible now. We need to take a careful look at some issues first:

• Mutability within iterators
• Can iterators be passed as arguments?
  • Mainly we need to consider if students will gain anything from this and is it worth the effort
• Over what types may we iterate?
• Are there any built-in functions we need to enable for these to be possible

[Sir-NoChill]

Iterators are a next step on the type system, we probably will need to wait until next year to properly get them.