Callback event calls

@param {object} el - popup instance DOM node
@param {number} ordinal - order number of an `open` element
@param {function} func - callback function
function (el, ordinal, func) {
        var options = $(el).data('popupoptions');
        var openelement;
        var elementclicked;
        if (typeof options === 'undefined') return;
        openelement =  options.openelement ? options.openelement : ('.' + el.id + opensuffix);
        elementclicked = $(openelement + '[data-popup-ordinal="' + ordinal + '"]');
        if (typeof func == 'function') {
            func.call($(el), el, elementclicked);
        }
    }