v1.138.0

# NautilusTrader 1.138.0 Beta

## Release Notes

Released on 15th February 2022 (UTC).

**This release contains numerous method, parameter and property name changes**

For consistency and standardization with other protocols, the `ExecutionId` type 
has been renamed to `TradeId` as they express the same concept with a more 
standardized terminology. In the interests of enforcing correctness and 
safety this type is now utilized for the `TradeTick.trade_id`.

### Breaking Changes
- Renamed `working` orders to `open` orders including all associated methods and params.
- Renamed `completed` orders to `closed` orders including all associated methods and params.
- Removed `active` order concept (often confused with `open`).
- Renamed `trigger` to `trigger_price`.
- Renamed `StopMarketOrder.price` to `StopMarketOrder.trigger_price`.
- Renamed all params related to a `StopMarketOrders` `price` to `trigger_price`.
- Renamed `ExecutionId` to `TradeId`.
- Renamed `execution_id` to `trade_id`.
- Renamed `Order.trade_id` to `Order.last_trade_id` (for clarity).
- Renamed other variations and references of 'execution ID' to 'trade ID'.
- Renamed `contingency` to `contingency_type`.

### Enhancements
- Introduced the `TradeId` type to enforce `trade_id` typing.
- Improve handling of unleveraged cash asset positions including Crypto and Fiat spot currency instruments.
- Added `ExecEngineConfig` option `allow_cash_positions` (`False` by default).
- Added `TrailingOffsetType` enum.
- Added `TrailingStopMarketOrder`.
- Added `TrailingStopLimitOrder`.
- Added trailing order factory methods.
- Added `trigger_type` param to stop orders.
- Added `TriggerType` enum.
- Large refactoring of order base and impl classes.
- Overhaul of execution reports.
- Overhaul of execution state reconciliation.

### Fixes
- Fixed WebSocket base reconnect handling.