Issue with $activeHeader in tabby.js

Hi there!

We’ve just encountered an issue with this plugin. The problem is that in tabby.js $activeHeader is assigned a value without using the “var” keyword:

$activeHeader = $activePanel.prev();

This is not a problem in itself, but in our case a caching plugin combines a bunch of files, and one of those files turns on JavaScript’s strict mode.. and when that is enabled, aforementioned row causes an error and tabs no longer work 🙂

To fix this, I’ve added var to my local version:

var $activeHeader = $activePanel.prev();

Would you consider making the same change to the official version of the module? Thanks in advance!