Thickbox support must change to colorbox in D7

Here's the patch, committed at http://drupal.org/cvs?commit=459298

Note that in Drupal 7 colorbox, there is a configuration you must do. See the INSTALL.txt:

Colorbox: If colorbox is installed (http://drupal.org/project/colorbox), the product images will link to nice larger images on the page. You have to enable "colorbox inline" at admin/config/media/colorbox. (Colorbox in Drupal 7 replaces the thickbox support in Drupal 6.)