Solved unexpected click events on BODY in Internet Explorer

Summary of the issue targeted by this pull request : Select2 triggers unexpected clicks on the body tag, but only in Internet Explorer. See issue https://github.com/ivaynberg/select2/issues/1058

This small patch only makes Select2 compatible with the XClick plugin I created here : https://github.com/louisameline/XClick. This plugin solves the x-clicks issue in Internet Explorer, which is more complex and may impact any scripts, not just Select2.

So, once this patch has been merged into Select2, users who wish to adress this click event issue can just insert the XClick plugin on their page and call `$.XClick()`. That's as hard as it gets.

Thanks !