Using a ProxyArray to get ListBox items handled correctly

Meant to not make a new branch, but I accidentally screwed up the old one when trying to revert it and decided to delete it. (See #992).

Anyways, to repeat: this intends to address #820.

This time my approach is an ArrayProxy that inherits from BasicObject and delegates everything to Array. 

Please let me know if this approach is good, needs tweaking, or needs a totally new direction (for example, how about `class ProxyArray < Array`?).

I have some questions / comments. I'll put those in-line before :poultry_leg: :sweet_potato: :fork_and_knife:  time!


Hmm, I think there's a little confusion here. The proxy's purpose in life is to stand between the user who called `items` and our array, so if we convert here we lose what the proxy provides.

We actually never want to hand out the un-proxied array, because then someone could muck about with it, and our GUI code wouldn't know about it.