* Oanda default forex Market
- Use Oanda as default forex Market since it has more pairs.
- Remove FXCM data add Oanda equivalente data.
- Update unit and regression tests
* Address reviews
- Revert FXCM data removal
- Remove unrequired commented code
* Fix rebase
- `CashBook[NullCurrency] { get; }` will throw an exception
- Revert `Currencies.USD` changes in user facing algorithms
- Improve some documentation
- Revert some format changes
- Adding more asserts for regression test
- Adding new regression tests using a custom fee model which returns
`OrderFee.Zero`
- Adding a non-usd account currency test to the cash book tests
- Adding some unit tests for `NullCurrency` and `OrderFee.Zero`
- Removing `AccountCurrency` from `Cash` and `Brokerage` classes.
`ICurrencyConverter` will now provide the `AccountCurrency`
- Adding new static `OrderFee.Zero` which will return a 0 order fee in
`NullCurrency`
- Adding static `Currencies.USD` value, replacing all "USD".
- Addin new static `Currencies.NullCurrency`
- Updating Bitfinex `FeeModel` so it return fees in quote currency.
Adding unit tests
- Replacing `decimal` for `OrderFee` at the `OrderEvent`.
- Adding `FeeModelNotUsingAccountCurrency` regression test
- Adding unit tests for `CashBuyingPowerModel` and `SecurityMarginModel`
with non account currency fees
Juan José D'Ambrosio