International Payments - set exact foreign amount

[awjdean]

The main voting thread for this feature is here:

Enter amount in foreign currency - International transfers

When doing an international transfer, I should be able to enter a value in e.x. Euros. Currently the only option is to enter a GBP value. If I’m paying someone in Euros, then more often than not I’m going to know the value I want to pay them in Euros, not GBP.