Game Time Calendar

1. Enable calendar command in the menu: $gameSystem.setCalendarEnabled(true)
2. Disable calendar command in the menu: $gameSystem.setCalendarEnabled(false)
3. Check calendar command is enabled: $gameSystem.isCalendarEnabled()

$gameCalendar.addEvent(data) - Add an event to calendar. Returns a created event.
data should contain the following fields:
name - String - Event name
start - Game_Time object - Start date/time of the event
end - Game_Time object - End date/time of the event
Additional fields:
iconIndex - Number - Icon index
location - String - Event location
description - String - Event description
switch - Number - Switch that turns on when an event occurs
Example:
$gameCalendar.addEvent({
 name: "Take the quest",
 iconIndex: 193,
 start: $gameTime.clone(),
 end: $gameTime.clone().addDay(1),
 description: "You must take the quest from the character \\i[4]Headman",
 location: "\\i[191]Headman's house"
})

$gameCalendar.getById(id) - Returns event with a specific id (or null).
$gameCalendar.removeById(id) - Removes event with a specific id.
$gameCalendar.getEvents(gameTime) - Returns an array with events (includes holidays) on the specified date.
$gameCalendar.getHolidays(gameTime) - Returns an array with holidays on the specified date.
$gameCalendar.isHoliday() - Returns true if today is a holiday.