Use get_the_image() if the theme supports it in hybrid_image_content().
Make sure to call the 'large' size image and don't use the 'meta_key' argument.  Also, return the original post content.
Use the 'post-thumbnail' size as a default in Cleaner Gallery only if it has been set by the theme.  Otherwise, fall back to the 'thumbnail' size.  This should work a lot better with themes that set a custom post thumbnail size with WordPress.
Remove support for post format images, which were removed from WP 3.6.
Major changes to bring the post format functionality back in line with WordPress 3.6's removal of the planned post format UI and accompanying functionality.  This change should bring us back closer to the original functionality packaged with the framework along with a few extra bells and whistles.