Add GPS Week Number to calendar

[skst]

I received this feature request in an email..

Thank you for making Timekeeper. I'm a retired land surveyor using it for my personal use and recently discovered it while searching for an easy means of knowing what the current day of the year it is (%j). This is very helpful for anybody looking for archived GNSS data at various repositories. It gets a little tricky, however, as we go back further and further in time from the present date as it requires counting back x days and then subtracting it from the present day of the year value.

There are other GNSS data repositories that need to know what GPS week it is (which began in 1980). Every 1024 weeks, there is a week rollover and is something you might recall being in the news a couple of years ago with the rollover's second occurrence.

One idea for your consideration as a Timekeeper feature request is to introduce a new format for displaying the calendar (e.g., %GPS).

I'm sure all surveyors and geodesists would love something like this.

[skst]

Here are some useful links for anyone who might want to implement this or a similar feature:

http://www.charlespetzold.com/blog/2009/10/Adapting-the-Calendar-Control-for-Week-Numbers.html
https://docs.microsoft.com/en-us/dotnet/desktop/wpf/controls/calendar-styles-and-templates
https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/june/customizing-the-new-wpf-calendar-controls