When you click on the button
hold festival a timer will start and will count down from 400 to 0.
When te timer hits 0 the bonus effect of 30% happiness will end and you have to spend another
5000 culture and
2500 Parchment to get the 30% happines bonus.
So a festival will take for 400 days and not until the end of a year.
Festival don't stack so if you have enough resources to start another festival before the first
festival is over you won't have a festival that is longer than 400 days
this.game.calendar.festivalDays = 400; //nope, they don't stack
this.game.msg("The cultural festival has started");
//TODO: some fun message like Molly Chalk is making a play 'blah blah'