function Querystring(qs) {
	this.params = new Object()
	this.get=Querystring_get
	if (qs == null)
		qs=location.search.substring(1,location.search.length)
	if (qs.length == 0) return
	qs = qs.replace(/\+/g, ' ')
	var args = qs.split('&') 
	for (var i=0;i<args.length;i++) {
		var value;
		var pair = args[i].split('=')
		var name = unescape(pair[0])
		if (pair.length == 2)
			value = unescape(pair[1])
		else
			value = name
		this.params[name] = value
	}
}
function Querystring_get(key, default_) {
	if (default_ == null) default_ = null;
	var value=this.params[key]
	if (value==null) value=default_;
	return value
}