function for opening a modal inject this method to the root model
function modalOpen (options) {
    if (isString(options)) options = optionsFromTarget(options);
    var modal = select('#d3-view-modal');
    if (!modal.size())
        select('body').append('modal').mount(options, vm => vm.model.$showModal());
    else
        modal.model().$update(options).$showModal();
}