Make GridForms variable accessible from other scripts

Hi Kumail,

Great work on gridforms.

We are using your project in a UI design we made.

Now I wanted to run the equalizing of heights from another script, but the GridForms variable wasn't accessible. This PR makes the GridForms variable from other scripts.

E.g. this is what we use to hook into GridForms' height equalizing:

    // Customization to equalize field height
    $(".select2").on("change", function(e) { 
      GridForms.equalizeFieldHeights();
    });