Send reminder email to appointments without order

[Valentina R]

If an appointment is created in the backend without an order, the reminder email is not set. Since the customer is attached to the appointment, I don't see the reason why we would not send it to the customer.

Not sure if this is a bug or on purpose.

Requested here: https://bookingwp.com/forums/topic/managing-appointments-admin/

[Željan Topić]

Fixed with 4.1.4