Market Account

- GetCash: refactoring

market_account.go

@@ -8,7 +8,7 @@ type MarketAccount interface {
 	GetName() string
 
 	// GetCash Cash Balance
-	GetCash() float64
+	GetCash(IgnoreBuyingPower bool) float64
 
 	// GetEquity cash + long_market_value + short_market_value
 	GetEquity() float64