Beginning of the week should be a calendar's property, but not a property in Lightning

This mail is about beginning of the week.  Let's call it BOTW for short.

Currently, the BOTW (Sunday, Monday, etc) is defined as a software-wide 
properties in Thunderbird/Lightning, ie
TB Options > Calendar (tab) > Views (tab) > General (section):
    Start the week on: xxxxx

However, for those who need to open shared calendars of other people, 
there can be a situation that one calendar needs Sunday as BOTW while 
the other needs Monday as BOTW.  For instance, someone in US shares his 
calendar so the BOTW is Sunday; while at the same time, most European 
countries including UK are using Monday as BOTW.

One of the consequences is the shift in week number.

Suggestion: move the "Start the week on:" option from Lightning 
(software-wide) to every calendar level (calendar-wide).

If you're OK, I'm going to post a bug/request in Bugzilla for this to 
keep the record.

Thanks