Add support for navigation dropdown menus on mobile / touch devices.
Navigation dropdown menus are widely used, especially on sites with lots of pages and/or categories, since they allow to go directly to almost every page of the site, with no need to navigate through all the intermediate pages in the hierarchy. Unfortunately dropdown menus do not work well with mobile / touch devices, because the "mouseover" event is not handled, so when the user click a top level menu, the browser follows the link instead of opening the dropdown menu. This plugin is a solution for that situation. On touch devices, the first click / tap on a top level menu (or, in general on any menu with children) only expands the nested dropdown menu, while the second one brings to the link. This is the same behavior natively adopted by iPad / iPhone starting from iOS version 5, so this plugin is intended to work with previous versions of iOS and with other mobile platforms that do not have such native behavior (Android, etc).