parse a date, create relevant object
fmt is in the format "abc%xdef..."
where abc and def is matched, and %x is
one of those time units:
%Y absolute year
%y year (70-99 is 1970-1999, 0-69 is 2000-2069)
%M month (number, name or short name) (needs %y)
%W week (needs %y)
%D date (needs %y, %m)
%a day (needs %y)
%e weekday (needs %y, %w)
%h hour (needs %d, %D or %W)
%m minute (needs %h)
%s second (needs %s)
function datetime(int|void unix_time)
Replacement for localtime.
function datetime_name(int|void unix_time)
Replacement for ctime.
function datetime_short_name(int|void unix_time)
Replacement for ctime.