Add email receipt option to POS screen after payment processed

It would much easier to send an email receipt if the option popped up after processing payment in the POS system.... at present you have to click through several extra steps.... from Orders, then click the student name, then their transactions list, and then you can email receipt. This should be a pretty quick easy add-on. You can print a receipt from the orders screen, which at least is only one step away. Many folks are fine with an email receipt rather than a whole sheet of paper when you've just sold a pair of tights.