Added support for Ticket Packages

We've recently added support for ticket packages throughout the MX API.

Ticket packages can contain one or more tickets and zero or more concession items. Ticket packages are added to an order in the same manner as any other ticket type.

This update impacts the following endpoints, so please check out the examples and comments for each:

• Get Ticket Types
• Get Showtimes for a Site including Ticket Types
• Create an Order
• Get Order
• Remove Tickets from Order
• Remove all items from an Order
• Get Screen Layout for Order
• Get Booking
• Partially Refund Booking
• Swap Seats for Booking