Online event ticket sales with alternative prices

When visitors open an event page and click Register, the ticket registration window now shows a second price next to the normal one. That extra price is the same ticket price expressed the other way round: if your website normally shows prices without tax, the alternative shows the price with tax, and vice versa.

• The alternative price appears both when the event has a single ticket type and when it offers several ticket types to choose from.
• Which price is shown as the main one and which as the alternative follows the website's tax display setting (show_line_subtotals_tax_selection).
• The price used is the ticket's reduced price, so any discount already applied to the ticket is reflected in both figures.
• The module adds no new menu or screen; it only changes the existing event registration window on the website.
• It works together with the online event ticket sales and the alternative price features, and installs itself automatically when both are present.

The change is limited to the event ticket model (event.event.ticket) and the website event registration template. No new business rules, checks, emails or scheduled actions are added by this code.