75ffa300f1
- Adding new `IAlgorithm.AccountCurrency { get; }` that will point to the
`Portfolio.CashBook.AccountCurrency`. Setter will be added in a
following PR.
- Base `Brokerage` class will now have a `AccountCurrency { get }`
pointing to the `IAccountCurrencyProvider`. Will be used by the different
brokerages implementations.