Array slices

[Mercerenies]

So it occurred to me that we already have this feature (or at least a read-only version of it). It would just be nice to make it a little more accessible. Specifically, if I want to get a slice of an array, I can just clone the array and change the bounds

arr := [1, 2, 3, 4].
slice := arr clone.
slice lowerBound := 1.
slice upperBound := 3.
slice printObject. ;; [2, 3]

Unfortunately, this is (1) incredibly verbose and (2) unidirectional. That is, changes to arr will be reflected in slice but not the other way around. We could pretty easily make a slice proxy object which allows bidirectional modification. The slice object would have mutable indices but would not have push or pop capabilities.

[Mercerenies]

Note that we would need to consider the impact of this issue with #32. Specifically, it would be nice to be able to slice into the #32 limited object as well.