It's all copied from your day/night demo I didn't change anything. I'm sure the problem with day coming back to 1 is because calendar event, because it happend only on the map with this event.
I found another problem. When you check the calendar and then close it, the date changes to the one where the mouse cursor was last time. So let's say I'm starting the game 1 day Spring, then open the calendar, push the next button it will change to 1 day summer, then when I press exit the date stays on 1 day summer on the map. It should just come back to the actual game in the date but it's not.