Parser für die SVgroup Menues

Usage:
http://imrof.li/svgroup/ -> Todays menu for the HSR
http://imrof.li/svgroup/?day=3 -> wednesdays menu for the hsr
http://imrof.li/svgroup/?day=5&mensa=technolino -> fridays menu for the technolino mensa
http://imrof.li/svgroup/?day=5&mensa=technolino&form=xml -> fridays menu for the technolino mensa in XML
http://imrof.li/svgroup/?day=3&weekmod=-10 -> wednesdays menu from 10 weeks ago


Days: from 0-5 (zero means today)
mensas: every mensa which uses the svgroup layout (like technolino or hochschule-rapperswil)
	it's the subdomain of the mensa (example: http://technolino.svgroup.ch.... -> mensa=technolino)
Formats: empty or form=html means HTML
		form=xml -> XML
		form=json -> JSON