Simul efun: format_date - get a string of date/time as you like it

Synopsis:
	mixed format_date(string format, int time)

Description:
	Returns the time/date formatted by the format-string or, if no
	format-string is given, an array (see below). If no time (in seconds
	since 1970-01-01 00:00:00) is given, time() (current time) is used.

	The format-string works like a (s)printf() format-string. But valid
	interpreted sequences are these:

	%%	a literal %
	%a	the abbreviated weekday name (e.g., Wed)
	%A	the full weekday name (e.g., Wednesday)
	%u	the weekday number (1-7, where 1 is Monday)
	%w	the weekday number (0-6, where 0 is Sunday)
	%b	the abbreviated month name (e.g., Dec)
	%B	the full month name (e.g., December)
	%m	the month number (1-12)
	%d	the day of month (1-31)
	%H	the hour (0-23)
	%I	the hour (1-12)
	%M	the minute (0-59)
	%S	the second (0-59)
	%Y	the year (e.g., 2003)
	%y	last two digits of the year (0-99)
	%p	AM or PM
	%c	date and time (e.g., Wed Jan  6 15:32:40 2016)
	%R	time (same as %02H:%02M)
	%T	time (same as %02H:%02M:%02S)
	%r	time (same as %02I:%02M:%02S %p)
	%D	date (same as %02m/%02d/%02y)
	%s	seconds since 1970-01-01 00:00:00 UTC (as returned by time())

	Of course you can use all (s)printf()-modifiers after the %.

Return value:
	with format-string a string, else an array of the form:

	({ /* sizeof() == 7 */
	  <string weekday>, // the abbreviated weekday name
	  <string month>, // the abbreviated month name
	  <int day>, // the day of month
	  <int hour>,
	  <int minute>,
	  <int second>,
	  <int year>
	})

Examples:
	write(format_date("Weekday:       %a\n"+
	                  "Month:         %b\n"+
	                  "Day of month:  %d\n"+
	                  "Hour:          %H\n"+
	                  "Minute:        %M\n"+
	                  "Second:        %S\n"+
	                  "Year:          %Y\n"+
	                  "Full date:     %c\n"+
	                  "Time:          %T\n"));

Note:
	The interpreted sequences are similar to the 'date' command's
	format-string on Unix-like systems. More of them might come ...

See also: lib/format_time, efun/time, efun/ctime, efun/printf