support OKX gateway

Author: 51bitquant

howtrader/app/cta_strategy/engine.py

@@ -552,7 +552,7 @@ def load_bar(
         end: datetime = datetime.now(LOCAL_TZ)
         start: datetime = end - timedelta(days)
 
-        # Pass gateway and datafeed if use_database set to True
+        # Pass gateway and datafeed if the use_database set to True
         if not use_database:
             # Query bars from gateway if available
             contract: Optional[ContractData] = self.main_engine.get_contract(vt_symbol)

howtrader/gateway/okx/__init__.py

@@ -0,0 +1 @@
+from .okx_gateway import OkxGateway