Amend the exchange rate when adding a Sales Receipt for a euro customer with a euro bank account

When entering a sales receipt for a euro customer to a euro bank account you can not change the exchange rate. If the currency is set to Euro then the exchange rate is taken from the Accounting system manager. If the currency drop down is set to Pound Sterling then the user can enter a £ value, amend the exchange rate and calculate the euro rate then enter this in the euro field. However, the exchange rate is ignored when the transaction is saved and once again its takes the Accounting system manger exchange rate. This means that the figure on the cash book account is using the amended rate and the figure on the nominal is using the accounting system manager exchange rate. Also similar to wish list number 4702.