Enable admin to set specific event as start page instead of standard page

[mariobehling]

Some event organisers might want to set up the system themselves for a specific event. In this case the specific event should be visible as a start page. Please add this option as follows:

1. In https://eventyay.com/admin/settings provide the option "Start Page" a) Use default start page b) Use event as start page with ID (Enter event ID here)
2. If the user chooses an event ID as start page show that event instead of the default start page.

[mariobehling]

The implementation does not yet work as expected. If the user clicks on the top left, the user gets directed to the standard start page. The current implementation for an event page as the front page is a forward to the specific event page. Is that already the solution we should go with? Other systems like Wordpress do not create a forward but instead they change the setting of the front page. What is the way to go?