Clearer order summaries for ticket buyers

We've been making some small, but mighty, changes to the way orders are displayed at checkout, and on invoices, to make it clearer to buyers what's in their cart.

What's new:

• A refreshed order summary design across the Dashboard, Checkout, and Self-serve pages.
• The order summary on the payment step of checkout is now collapsible, helping improve conversion.
• Cleaner invoices that group items by event or store, and include any credit from transferred tickets as a line item.