/* 
 * Вычисляет Timezone клиента с учетом DST
 */
function calculate_time_zone() {
	var rightNow = new Date();
	var jan1 = new Date(rightNow.getFullYear(), 0, 1, 0, 0, 0, 0);  // jan 1st
	var june1 = new Date(rightNow.getFullYear(), 6, 1, 0, 0, 0, 0); // june 1st
	var temp = jan1.toGMTString();
	var jan2 = new Date(temp.substring(0, temp.lastIndexOf(" ")-1));
	temp = june1.toGMTString();
	var june2 = new Date(temp.substring(0, temp.lastIndexOf(" ")-1));
	var std_time_offset = (jan1 - jan2) / (1000 * 60 * 60);
	var daylight_time_offset = (june1 - june2) / (1000 * 60 * 60);
	var dst;
	if (std_time_offset == daylight_time_offset) {
		dst = 0; // daylight savings time is NOT observed
	} else {
		dst = 1; // daylight savings time is observed
	}
	var gmt = new Date().getTimezoneOffset() / 60;
	gmt = -gmt;
	return gmt-dst +';'+ gmt;
}