Returns the weekday name of the date specified, in the current locale language
string uWeekdayName([modifiers]);
uWeekdayName("now") // returns current weekday name
uSetLocale("English") uWeekdayName("1969-03-13 10:22:23.231") // returns "Thursday"
uSetLocale("German") uWeekdayName("1969-03-13 10:22:23.231") // returns "Donnerstag"