Fixes: Deposit

[aryabhuptani]

Some issues with deposits:

1. I don't think you need a separate initialDeposit in the struct. Especially if you restructure the arrays into deposits[4] //0. ethA 1. ethB 2. erc20A 3. erc20B and balances[4] //same structure. This would also really simplify a lot of the logic while closing I think

2. I'm worried about the implications of deposit() for disputes. What happens if a user deposits money while having a VC open and Ingrid refuses to countersign a new LC update? User can challenge with VC_S0 but that doesn't contain deposit in it. Maybe I'm misunderstanding here, but we should chat about it @nginnever

[nginnever]

The reason I tracked deposits separately is specifically to avoid case 2. I think we should have a chat about why this is the case as others seem to not understand this issue as well and maybe there is a cleaner solution than tracking deposits.