Simple calendar extension for mediawiki.
	
	Released under the GPL. Copyright 2005 by Christof Damian
	(christof@damian.net)
	
	I wrote this for http://krass.com/ where I have simple event
	calendar. Examples are at http://krass.com/wiki/Current_events and
	http://krass.com/wiki/Calendar
	
	The idea was to keep the calendar as simple as possible and leave all
	the editing and page creation to mediawiki. It doesn't require any new
	database tables or files.
	
	To use this on your mediawiki site, copy the "calendar" directory into your
	extension directory and put this somewhere at the end of your 
	"LocalSettings.php":
	
	  require_once("$IP/extensions/calendar/Calendar.php");
	
	Then you can use the calendar on any page like this:
	
	<calendar>
	name=mycalendar
	view=year
	</calendar>
	
	The parameters work like this:
	
	"view"
	       can be "days" days from today, "rdays" (reverse days),
	       "week","month","threemonths", "year" (default), "weeks" and "months".
	"name"
	       is a name for the calendar and changes the names of the day pages.
	"format"
	       defaults to '%name_%year_%month_%day' and describes the names
	       of the day pages.
	"formattitle"
	       formats the titles in today/days/week view
	"day","month","year"
	       you can specify the date of the calendar, it defaults to today.
	       currently this doesn't work with "view=week"
	"date"
	       this takes a php strtotime ( http:://www.php.net/strtotime )
	       option and overrides the "day","month","year" option
	       above. examples are:
	
	       date="+1 week"
	       date="next monday"
	       date="+7 days"
	"enddate"
	       just used for the weeks view, this is the last date to display in the
	       weeks
	"weekstart"
	       week starts on 1=monday ... 7=sunday. default is 1
	"skipempty"
	       skip empty days in week view
	"showempty"
	       show inivitation to add entries when a day is empty, default is 1
	"weekformat"
	       format of the week, days, rdays and today view.
	
	       - "text" (default), simple wikitext format
	       - "list" a layout that uses <dl>, <dt> and <dd> (definition
	         list) tags with the 'calendar' class added to the <dl>
	         tag and the calendarToday class to the span tag that
	         contains the weekday title. Merged calendar
	         entries are added as sub lists with the name part of the
	         merged calendar as a link to the page of that
	         calendar.
	       - "table" a layout that uses table tags with also the name of
	         merged calendars as a link to the page of those
	         calendars. The 'calendar' class is added to the table tag and
	         the 'calendarToday' class to the span tag that contains the
	         weekday title.
	"months"
	        number of months for the "months" view
	"mergemonth"
			include the day page in the month, months and year views
	
	format & formattitle accept these substitutions:
	        %name
	        %day,%month,%year
	        any php date() substitution prefixed with '%', like '%m','%d','%Y'
	
	Thanks go to these contributors:
	
	- Amador amador@tiscali.nl (localization, weekformat, showempty)
	- Austin Che (cache fix)
	- Dexter Samida <dextersamida@gmail.com> (today view)
	- Kai Sommer (months view)