amount is overridden, extra parameters are copyto payload also. extra parameters for loop is useless so it override only price without using key/value of extra parameters (#548)

Author: gungoren

src/ExchangeSharp/API/Exchanges/Bitstamp/ExchangeBitstampAPI.cs

@@ -205,12 +205,6 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
                 payload["price"] = order.Price.ToStringInvariant();
             }
 
-            payload["amount"] = order.Amount.ToStringInvariant();
-            foreach (var kv in order.ExtraParameters)
-            {
-                payload["price"] = order.Price.ToStringInvariant();
-            }
-
             payload["amount"] = order.RoundAmount().ToStringInvariant();
             order.ExtraParameters.CopyTo(payload);