This fixes:
- Fixed bug #72719 (Relative datetime format ignores weekday on sundays only).
- Fixed bug #73294 (DateTime wrong when date string is negative).
- Fixed bug #73489 (wrong timestamp when call setTimeZone multi times with UTC
offset).
- Fixed bug #73858 (first/last day of' flag is not being reset).
- Fixed bug #73942 ($date->modify('Friday this week') doesn't return a Friday
if $date is a Sunday).
- Fixed bug #74057 (wrong day when using "this week" in strtotime).
