VATSIM PHP Scheduler, using VATSIM GERMANY API.

It is recommended to set up a separate PHP file for each overview you would like to create. Alternatively one file can be created that outputs images to files using a cronjob.
If multiple overviews use the same stations, optional stations or wanted stations, a central config file might be useful.

A new Overview is created by making a new instance of the Schedule class:

```php
$schedule = new Schedule($displaydates, $stations, $optstations, $wantedstations, $darkmode);
```

* `$displaydates` is an Array that should be created with one of the helper functions:
    * `Schedule::EveryXDaysFromStartdate (String startdate, int x, int numberofdays = 1)` - Returns an array of DateTime objects. For regularly recurring events. Define a startdate and an interval in days for the event. numberofdays defines how many upcoming days will be returned.
    * `EveryXWeeksFromStartdate (String startdate, int x, int numberofdays = 1)` - Returns an array of DateTime objects. For regularly recurring events. Define a startdate and an interval in weeks for the event. numberofdays defines how many upcoming days will be returned. This is just an alias for EveryXDaysFromStardate with the input for x being x*7.
    * `EveryWeekday (String weekday, int numberofdays)` - Returns a list of datetime objects. This can be used for weekly events. Define a day of the week (such as "Wednesday") and the number of days to be displayed.
    * `WholeWeek (int shift = 0)` - Returns a list of 7 datetime objects for consecutive days. Will start with today + shift days.
* `$stations` - an array of the stations that are to be displayed (including optional ones!). The String `--` can be used to display a visual seperator.
* `$optstations` - an array of the stations that are only to be displayed when there is a booking for that station. Defaults to `[]`.
* `$wantedstations` - A 2-dimensional array of stations and dates that should show "Wanted!" instead of "Open" when no booking is made. Defaults to `[]`. A helper function to create this array is provided:
    * `Schedule::processWantedDays(array stations, array dates, ...)`: In pairs of stations and dates each, provide as many pairs as needed. Stations should just be a plain array of stations, dates should once again be an array of DateTime objects, ideally using the helper functions described above.
* `$darkmode` - Whether to display a dark or light background. Defaults to `false`. The attached `darkmode.php` provides a way to set a cookie for the darkmode which can be used to feed this value.

The image will be creted calling the `createImage` method.
```php
    $image = $schedule->createImage();
    imagejpg($image);
```