Bug: the weekday tooltip is mismatched when user changes the first day of week from Sunday to another day in Settings

[Maples7]

For instance, when I change the the First Day of Week from Sunday to Monday

The grid adjusts well accordingly (BTW, it's Monday on April 1st while I'm typing...)

But the weekday tooltip doesn't change accordingly.

It still marks the second row as Mondays.

[Maples7]

Just opened a PR to fix this: #13

@jasudev thank you for creating this nice UI library, could you please help review this issue and the related PR to fix it? Thank you very much! :D