[Feature request] Add the option to start the week from other day (sunday)

[michael-gabbay]

Describe the bug
In some places the 1st day of week is sunday and not monday,
therefore it will be very useful in weekly planner to consider it and allow to pick the 1st day of week

To Reproduce
N/A

Expected behavior
Setting to change the 1st day of week,
once changed to sunday, weekly planner will show the week from sunday to saturday

Thanks for this great plugin!!