function RemoveTemplate($id_tm, $i_quantity = false)
	{ // removes an item from cart, but leaves template info
		$this->aCart[$id_tm]['quantity'] -= intval($i_quantity);
		if (!$i_quantity || !$this->aCart[$id_tm]['quantity'])
			unset($this->aCart[$id_tm]);
		$this->_update_total();
	} //end of del_item