Prevent event currency options being shown in Multiple Bookings mode.
As that would make a right mess of the cart / checkout process.:wq
Change currency display if custom currency set on event
This is a two step process due to EM's helper function
em_curr_get_currency_formatted not being event or ticket aware.
We check if the currency needs changing by hooking into
em_ticket_get_price, setting a global var if this is the case.
Then we hook into em_get_currency_formatted and modify if required.
Hook into SagePay and modify currency value if set on Event
Added Readme