Enhance open listener to allow 3rd party js click events as well. #38

Currently due to https://github.com/codrops/ResponsiveMultiLevelMenu/blob/master/js/jquery.dlmenu.js#L123 any 3rd party JS set to listen for clicks on those menu items for whatever reason never get triggered.

If you are going to call event.stopPropagation there then do it conditionally for the situations you deem it necessary, not on all clicks, which is not needed.

To clarify the situation, several WP themes use this library. When combined with a plugin like my own (Popup Maker) the user wants to be able to trigger a popup from the menu item, everything is set up correctly except that line prevents it from triggering the popup so it just sits there doing nothing.

Hope that is clear what we are hoping for.