Order

- refactoring GetSize()

order.go

@@ -8,7 +8,7 @@ type Order interface {
 	GetSymbol() string
 	GetAction() OrderAction
 	GetTimeInForce() TimeInForce
-	GetSize() int
+	GetSize() float64
 	GetPrice() float64
 	GetCurrency() string
 	GetStatus() string