They use minified versions for size constraints, and these versions are the standard. You’ll see minified JQuery libraries just like this in most feature-rich plugins.
It’s not PHP code, either. It can’t be run on your server, only downloaded by the end users.
That file (jquery.easing-1.3.pack.js) is not malicious at all. It’s a JQuery library, and the developer used the “minimal” version to make it smaller. We do this all the time. If you want to see the full version, do a google search for it.
