prinds's sandbox: Overlay helper

Overlay helper makes the overlay able to remember and restore the scroll height of the parent window once the overlay closes. This also works, when the parent window is being redirected e.g. after a save action, because it stores the scroll value in the window.name variable.

For now this module relies on a patch of the overlay.module, that adds two extra javascript events, which needs to be triggered in the overlay-parent.js:
- drupalOverlayBeforeOpen
- drupalOverlayCloseDone

You can find the patch here : https://drupal.org/files/extra_events_for_overlay-1918692-1.patch

There issue requesting the extra js events can be found here : https://drupal.org/node/1918692