Add Tether integration

[v-stickykeys]

Hey everybody! I've been thinking about trying to model first order effects of Tether getting rekt (by prosecution, rug pull, or similar), and I was wondering if one of you fine folks might be able to help me use God Mode to do so. Thoughts?
(I assume that it would cause a large catastrophe in Maker, larger than Black Thursday, and maybe also rek the Curve 3pool. Some of that is likely second-order, though - Maker liquidations are manual events, I think, so I'm not sure I'll be able to capture all of that.)

[martinetlee]

Tether unfortunately doesn't have its contract code open source (so cannot be easily modified via the library itself)
We'll need to reverse engineer which storage it is trying to access, then access those directly.

[v-stickykeys]

@martinetlee so it's not this? https://etherscan.io/address/0xdac17f958d2ee523a2206206994597c13d831ec7#code

[martinetlee]

Ah wait, seems like it is open source. Then I must have incorrectly mixed it up with another coin. In this case it would be pretty easy. What was the effect he want to model? Infinite mint?

[v-stickykeys]

@martinetlee details are on discord. Can we get on a call to discuss? and probably @benjamistan can provide context as he spoke with William.