Add the option of changing the first day of the week

[phins3555]

Please add the function to change the first day of the week.

[Jaimies]

That sounds like a pretty good idea, though I have the suspicion it would take quite a bit of work, especially because if I recall correctly, the app stores the time/distance/etc. separately based on the day, month, year, and week (while making the assumption weeks start on Monday), so to implement this feature we might have to take care of that.

I have no plans of working on this feature, but I'll be glad to review and merge a Pull Request. I'll be keeping this issue open because this really is a nice feature to have.